"How it all works is a long explanation, or at least a long list of short ones; how much do you want?
I can't do it myself because some of the other elements don't naturally exist. Well, the elements all do, but there's no known way to get some of the the pure metals from the compounds they're found in. And until Fairyland, ability to not eat was never a priority anyway."

"If that's the constraint, we should be good with time.

Okay, so there are three types, Allomancy, Feruchemy, and Hemalurgy.
Allomancy is the well-known one. An Allomancer swallows a metal, and can later 'burn' it for a predefined effect. This is why I had vials of metal on hand in Fairyland. Most Allomancers can only use one type of metal. They're called Mistings. Some—Mistborn—can burn any Allomantic metal.

There are sixteen relevant metals plus a pair made entirely of the concentrated power of Preservation or Ruin.
These metals are: Steel, which when burned shows bright blue lines leading to any nearby metal from your center of mass. And it allows you to telekinetically push along those lines. Iron is the same except it allows you to pull. These metals are also the primary sense of the Inquisitors.
Pewter makes the Allomancer stronger, tougher, faster, and basically physically better in every way. How much better depends on how quickly it's being burned, and anyone who overuses it will hurt in the morning. Tin strengthens the senses in a similar way.
Zinc and brass are the emotion-affecting ones. One strengthens emotions and one weakens them, but since people have at least some of most emotions nearly all the time the effects are similar. Burning bronze detects nearby Allomancy, and copper protects against the previous three.

Those eight are the only commonly burned metals; the others are either rare, nonexistent, or near useless.
The ones made of Preservation and Ruin are called lerasium and atium respectively. I doubt you could make those with sorcery. Lerasium will turn anyone into a Mistborn and atium will show the Allomancer what their opponent's next action is going to be. It makes a Mistborn all but unstoppable if the opponent is not similarly equipped.

Metals, obviously, do not intrinsically contain any such abilities. All they do is provide a focus for people who are capable of drawing on the power of Preservation in prescribed ways. This is why I couldn't use Allomancy in Fairyland: there is no power of Preservation there, so burning any metal other than atium or lerasium would connect to nothing at all.

Should I explain further, or go on with the next two?"

"Feruchemy is what I was using on Fairyland. It's not drawing on Preservation or Ruin; the power is from the practitioner themselves. A Feruchemist can store their own attributes in a piece of metal for later use: Weight, physical speed, mental speed, senses, strength, warmth, memory, wakefulness, and health are the common ones. For each of these they need a corresponding metal. Weight can only be stored in iron, health in gold, and so on. That's why I'm wearing so much metal.

Since it's storing your own abilities, the amount you get out is equal to the amount you put in. Spending some time at half your normal speed will allow you to be half again as fast for the same time, or twice as quick for half, and so on. To cure a fatal wound, a Feruchemist would have to spend an awful lot of time with a cold.
This is also where the ability I offered you comes in. By Feruchemically storing all your sense of hearing, you could become temporarily deaf at will. You'd want a tinmind for each sense, but the relevant one is hearing.

Feruchemy works on the principle that what you put in is what you get out. There's an exception. If the Feruchemist is also an Allomancer capable of burning the metal in question, they can burn a charged metalmind. Instead of the normal Allomantic effect, this will give them several times the Feruchemical attribute stored in the metalmind. This extra can then be stored in another metalmind, and possibly burned again for even more of it.
Since I'm both a Feruchemist and a Mistborn, this gives me an effectively infinite supply of any attribute that Feruchemy can store, limited only by whether I have enough metal to store all of it. If I had bendalloy that could include food, and if I had chromium it could include luck. That one I'd be very interested to test. Atium can store youth. This, combined with the fact that I can burn a charged metalmind, is how I've lived so long.

Hemalurgy is the practice of stealing an attribute from someone else. This can be physical strength, physical senses, or any Allomantic or Feruchemical power. Having an attribute stolen is almost always fatal. The transfer is powered by Ruin, and so unlike Allomancy or Feruchemy it's a net loss. It would take several spikes' worth of the same attribute to bring someone with none of an ability up to the same level as a typical Misting or Feruchemist.

Theoretically Hemalurgy can also steal anything that's intrinsically a part of someone's...I suppose the closest word is soul. I don't know how to use it for anything I haven't listed, but it means it might be possible to steal immortality. Which we've been over.

And yes I know what your opinion of Hemalurgy is likely to be."

"Do you have any live victims of hemalurgy lying around?"

"I would be very surprised if that's even theoretically possible, but it's a moot point. There haven't been any in centuries.

I hope you won't refuse the spikes that can give you the deafness ability because of their origin?"

"That is possibly the strangest preference I've ever heard of," says the man under a truth compulsion. "But once we're established as a group that exists in Fairyland we can spread the word that it might be an option.

If it helps, there'd obviously be no need to even ask if it involved killing anybody. There are some Inquisitors who don't need Feruchemical tin as much as you do; I can just take the spikes that they're getting the ability from and stick them in you instead."

"Yes. To start with, anyway." He could use mind magic to make it so that she doesn't mind the discomfort, but that's extraneous to the answer and he chooses not to bring it up. "Once the first spike is touching your blood, you'll have the ability to store senses, and if you use that it'll be much less uncomfortable. By the end of it of course you'll be able to block out a sense entirely; that is the point after all.

And it will heal much more quickly than a mundane spike would, but I'd suggest not using sorcery to speed it up. I don't know how it'll interact."

"It works fine with Feruchemical and Allomantic healing, but I don't know how sorcerous healing works. And it does slightly change the structure of the body. Mostly it reroutes blood vessels but in extreme cases—which this isn't—it might shift organs or even bones.

As for where, there are hundreds of bind points around the body. This one is rarely used and kind of obscure. I stored the information in a coppermind and can't answer your question without first using copper Feruchemy."

He draws on a coppermind—it comes with an intuitive sense of which one—and then says "It's on your arm just below the shoulder, at an angle of about sixty degrees in either direction from straight sideways. At least for a human it is. If fairies are different, we'll find out as soon as it pierces skin and nothing happens."

And then, since he doesn't know if he'll get another chance, he stores a bit of knowledge for later in an empty coppermind.
That knowledge is that he can use Feruchemy to selectively forget things.