Alicornutopia

Maggie's kind magic variant is more powerful but more aesthetic and overall better than the bare "sex swap" kind magic.

What's the technology like in fairyland? If you brought, say, a computer, would it stop working there? How interested are fairies likely to be in technological artefacts? How (un)prepared are they likely to be for them?

You'd need to bring a solar charger.

Also, how figure-out-able is sorcery without instruction?

Technology works in fairyland, modulo things like "does this require the rotation of the earth" and stuff like that. Fairies are likely on average to be curious about tech things and blindsided by them if they're deployed effectively.

You could eventually figure out sorcery without instruction for a value of "eventually" that assumes you're immortal; that's how fairies did it.

If you had access to an introductory volume on sorcery, would that give you enough of a base to figure other things out without having to take hundreds of years? Like, say, how long approximately would it take you to figure out how to gate?

Assuming you were firmly convinced that gating was possible and didn't get discouraged, maybe two to five hundred years depending on talent and lucky trains of thought.

So with book at least two years, without book two to five hundred years. Yikes.

Would fairies barter for technology with a mortal? Or would they be too focused on trying to acquire a pretty vassal to care? Or does that vary enough that either could happen or something else entirely?

Fairies vary plenty.

How does name-learning sorcery work? How much contact with a person do you need for it to work?