Magnetism is caused by a difference in electron energy levels, to make a long, long story short. Thusly, there are many magnetic compounds which don't contain any form of iron. There are also thousands of heavy metal (rubidium, niobium, magnesium, chromium, copper, silver, nickel, Germanium, silicon, arsenic, etc. -- basically, anything in the 'transition metal' part of the periodic table, and they're in almost everything) compounds and heavy metals which make magnets that are hundreds of times stronger than a normal ferrous magnet. Magnus has shown an incredible degree of ability and skill with this. Able to work on a molecular level he can alter the shape and densities of metal to what he can imagine. He has a range of nearly three miles, but his control in this diameter depends entirely on how close the object is to his person. Within a half a mile his control is complete, but the further you are removed the less his ability to effect it, and sense it. At the full distance, Magneto can do little more than move a thing around, and without any great deal of delicacy.
His strength level is huge, with a capacity of over 25,000 tons. In X-Men issue #1, Magneto lifted a Russian submarine off the floor of the ocean. As this was about the only example I could find for the limits of his lifting capability, I went out and looked up the weight of a Russian Typhoon-class sub. It has a weight of 26,500 tons and a full displacement of 48,000 tons. This also does not take into account that said submarine was full of water (the weight of seawater is over 64 pounds per cubic foot) and was on the floor of the ocean (at 1150 feet down the water pressure can be over 500 pounds per square inch). These two factors would have raised the weight by multiples, and so his lift would really be well beyond that 25,000 number. As a sidenote, this weight limit is for metal only -- Magnus can lift objects that contain little metal, but the less metal within an object the less of it he can lift. Basically, it's directly proportional to the metal contained therein.
He can also sense metal, allowing him to know any that is within the vicinity of his power range. It has never been told what sort of metals he was able to detect, but I believe it to be all metals. Large concentrations are of course easier to detect than small ones, but if he was specifically looking for a piece of metal, he'd definitely find it.
Magneto generates high levels of bioelectrical energy, and we're taking immense levels of energy. Enough so that he's literally creating ozone simply by existing. Wherein most people, ATP synthesis ends with the electrons being plugged back into the beginning of the cycle, in Magnus, they're dumped wholesale into his nervous system, which is made of something very like myelin and nerve tissue, but with a much higher conductivity. Although much more difficult than his magnetism power, Magnus can create short bursts of electricity which can be directed towards an intended target. Electricity is just electrons moving down something like a copper wire or even air. This ability is not often used because of how difficult it is to generate and control.
There are millions of compounds which could be made 'super-magnetic' by a simple disruption of electrons. And when you mess with the electrons in a compound, shoving them into higher energy states, the compound heats up. Simply put, he can generate small fields of heat, even perhaps to direct it in something close to a beam attack. But this is incredibly difficult, and has never been shown in the comics. He could feasibly create fields of temperatures hot enough to peel paint off walls, and ignite most combustible compounds.
Now, in altering the spin of electrons, and being able to cause them to not only jump to higher energy states, but to drop to lower energy states, Magneto is able to generate electromagnetic radiation. In other words, high-energy light, x-rays, gamma rays, both hard and soft UV, and visible light. He could cause radiation damage/burns if he chose to create flashes of x-rays or gamma rays. This takes a great deal of his concentration, and I doubt he would do it for the fact that Magnus himself is not immune to radiation at such levels. Yes, he is immune to low levels of it for he emits higher levels of radiation than a normal human due to his powers, but anything of the levels that I mentioned above would be fatal.
He could also create flashes of UV light that would damage human retinas, blinding individuals partially or fully. He could possibly even create lasers, and/or stop laser attacks by dispersing the light, thus rendering it harmless. These are not fully detailed as he has never been shown in the comics doing anything like this. To do any sort of direct light manipulation would take a great deal of his concentration. Now, most of his other power effects give off light as a byproduct of the sheer power levels that he is trying to wield. This is for the most part only a harmless illumination and not some form of attack.
Light moves though the world on waves, and these waves can be controlled with electromagnetism. One of the most interesting aspects of this is the ability to warp light, basically rendering one almost completely invisible. This is like the effect in Predator, where the creature warped the light about itself so that it blended in with its surroundings. Now, while moving, anything covered in this field of warped light is going to leave a slight, visual disturbance. If Magnus were to have this effect up, and chose to remain still he would be nearly undetectable via sight.
It also grants him the ability to detect invisible or cloaked creatures and objects by tracking their movements along the magnetic lines. All living things generate bioelectrical energy, as well as electromagnetic radiation. Magnus just senses it personally, rather than with the intervention of machines. Because of this bioelectrical energy, even an invisible person is going to create a disturbance within Magnus' sensing range.
Ever seen two magnets repel each other? Magneto can create, in the very air around him, what are in essence gaseous ultramagnets out of the ions around him. These ions 'adhere' to him in a 'coating', and with a thought, he can flip their polarity to be the same as that of the earth's magnetic field, allowing for flight. In issue #112, Magneto was flying along by himself and was matching the Avengers Quinn jet. After talking to some others I have guestimated this speed to be around Mach two (1500 mph). This is when flying alone, however. When carrying people this speed drops considerably for the amount of concentration it requires to both attune to the Earth and protect those he's carrying from the elements and the effects of magnetism.
Effect on Plastics
Magneto can alter the spin and energy levels of electrons, giving him control over anything which has d-shell electrons, or pseudo-d-shell electrons (that'd be any element from potassium on up). Those kinds of elements are commonly used in making resins, which would give Magneto some control over some plastics. I'd say that if he can affect blood because of iron, he can affect plastics due to the ionic impurities from the process of making said plastics. Of course effecting plastics is much, much more difficult than effecting direct metal. Of course, if someone went through the trouble of creating a plastic which couldn't be effected then Magnus simply couldn't effect it.
Magnus is able to create an electromagnetic pulse that would disrupt or destroy any technological equipment within a few hundreds of miles. It would blow nearly every resistor and fuse, but unfortunately, this type of radiation adversely effects humans as well. Anyone within a few feet of the source of the effect would be given a normally lethal doze of radiation. It would also effect the brain waves to some extent.
Wave of Force
Slam two electrons together and you get energy. Slam enough of them together at once (enough actually means like three or four -- it wouldn't take much.) and you get a devastating wave of concessive energy akin in nature to a 'sonic boom', capable of fusing sand into glass, knocking down buildings, and destroying anything living in its path. Magnus can achieve devastating force for a radius of two blocks. Anything outside of this radius will have diminishing effects.
Effect on Iron in Blood
As the title suggests, Magnus can effect the very iron in the blood of a living being. He uses this effect commonly to hold people immobile, to lift them, throw them about, or even causing anemia, weakness, or fatigue. Hemoglobin contains, at the heart of the protein structure, six iron molecules, one per subsection. These iron molecules are in a certain ionic state; that is, they must be Iron 3+ molecules. Magneto can change the ionic state of these iron molecules to Iron 2+, which renders the hemoglobin inactive, and red blood cells incapable of carrying oxygen.
Magnus takes ions and forms a shell of 'ultramagnetism' about the area he's protecting. Unfortunately, the strength of these shields is nearly impossible to quantify. Also, as he desires these shields can be completely air tight, even to the effect of containing an environment. Remember that air is a mixture of nitrogen, which contains p-orbitals, oxygen, which also contains p-orbitals, and other heavier gasses. It's only about 3 percent hydrogen, and 3 percent helium. The force field works from both sides-- as the air molecules 'bonk' into it, trying to escape, they are repelled from the ultramagnetic gas, back towards the center of the force field. The diameter of his force field can be as large as one block.
Magnus commonly uses his shields to protect him from the vacuum of space. His air limit is only a couple of hours; even less should he choose to have other people with him. The more people he carries the less time his air will hold. These shields are highly obvious as they crackle constantly with bright blue electricity. By the very nature of this power, Magnus can hide from detection what is in the field, but not the field itself.
Telepathy is a mental effort by the probing telepath. What they're doing is what Magnus does-- they're reading static/active bioelectrical patterns. But Magnus generates so much electrical energy that he's essentially unreadable. Only the most powerful telepath's stands a chance of breaking through.
The human body is, in essence, a giant biochemical battery. The electrical impulses along myelin sheaths are our thought patterns. And patterns they are -- static patterns store memories, and non-static patterns contain thoughts. Magneto can distinguish both, and after years of practice, has become adept at 'reading thoughts'. Of course, this is not easy. It requires physical contact with the victim, and is rather painful for said victim. Also, his method has very little finesse and he can only gain surface thoughts.
Pull the Metal out of Objects
This is something he has been known to do many times. Magnus can pull the metal out of the ground to form shields or objects he deems necessary.
All living things generate bioelectrical energy, as well as electromagnetic radiation. Magnus just senses it personally, rather than with the intervention of machines. And it's a known fact that your emotions cause your body temperature/bioelectrical patterns to fluctuate. Normally I would think he keeps this ability to within a few feet of his person for he has no interest in being able to sense the hundreds of people that normally inhabit cities and the like. He can distinguish people by the 'feel' of this aura alone, and doesn't necessarily need to be able to see them. Magnus' vision does extend very little beyond that of a normal human. He can see into the IR and UV light spectrums, but not all that well. To Magnus most people are surrounded by a faint, hazy field of energy that changes as their bioelectrical patterns fluctuate.
Magnus can cast an image of himself anywhere within the boundaries of his power range. This image is obviously not real because it appears as a ghost-like form. He can form what is basically an image composed of light; he can force the electrons in a room to give up energy, creating patterns of light in much the same way as a cathode-ray tube would. It's sort of like the screen on your TV set, except that it's massless. Magnus can not use his powers through it nor can he use his powers while the astral image is being used. While he is casting the image his own body is vulnerable to attack as his attention is obviously elsewhere. These projections can only be held for a few minutes.
This is not quite what it sounds. Magnus can, during flight, move into the upper atmosphere, and stop himself from moving in relation to the Earth spinning; or move, due to these 'ultramagnets', the opposite direction of that the Earth is spinning in. It may not sound like much, but it can allow him to travel at speeds of roughly 3000 miles per second.
Magnus can create stirrings in the air itself by generating gaseous ultramagnets from the ions present in the atmosphere in varying patterns. When the poles of the ultramagnets are the same, the ultramagnets repel each other with enough force to create a low pressure spot in the immediate atmosphere. When the poles of the ultramagnets are different, the ultramagnets attract each other, moving with enough force towards each other to create a high pressure spot in the atmosphere. By doing this in varying patterns, Magnus can create tidal winds of hurricane velocity, whirlwinds, or other wind-based weather effects.
Photosynthesis and ATP Synthesis
Magneto would also able to affect photosynthesis in plants, causing it to come to a halt, and the plant to die; since that's an electron transport process. Also, it's possible to affect ATP synthesis in humans, since that's another electron-transport process. In any living tissue or substance, he could generate excited states of electrons in compounds, which are commonly known as free radicals. Free radicals are, to put it bluntly, really bad things. They can kill you very quickly.