No ATT required for non-restricted arms.

IIRC, a letter from your former local police is most useful for this process, but we've got a couple former foreigners kicking around here someplace that could probably offer a more in depth view of the process.

There is some paperwork you can fill out to import your own firearms into the country, less trouble for you since you're a US citizen I would think. There are also some importers (like Aztech at the top of the page) that can help out with the cross border bit.

The range is a great place to meet people, as well as the local gun shop. There's also a BC group of GOC'ers that gets together for coffee and such once in a while, they've got a thread about it around here somewhere....