If you have criminal history, no matter how long ago, learn about it and check with customs. Lots of stuff is NOT a big deal, but as mentioned, stupid stuff like a DUI is a NO GO. No matter the age.
As for what to bring with you. Maybe you should have more but I have never had to show more then just my passport. I used to bring sled registrations etc. and obviously truck has reg/insurance in it. But usually you show up, show passport, answer a few quick questions and off you go.
Letting credit card know you are travling is always smart. As mentioned, they are hard to beat for exchange rate handling. Cash is sort of dumb to jerk around with.
Trail passes. If your riding main zones in revy you have to buy a daily pass which is 20 or 25 a day. Purchased at trailhead. More remote zones have nothing. Go ride and enjoy! Make sure to check the maps depending on zones and know about the caribou closures. Usually well signed. Just nice to plan rides accordingly.
http://revelstokesnowmobileclub.com/