Your Visa will work as long as you call and let them know but depending on your plan, may want to switch money ahead. I'm normally lazy and just take cash out at an ATM when I get there, I probably don't get the best exchange when I do. Canadian places will also often accept US, but we're usually jerks about it and take it on par because we don't want to convert it, so you're losing out a lot if you go that route.
Same plugs up here, which is a huge thing to remember if you do switch continents, but as a general rule any large airport sells converters. I got a nice set in the mini airport apple store. So you won't have to worry about that.
Liquids, you do just pack them in a plastic bag, they can't be over 100 ml each, easiest if you pack them somewhere you can pull out easily when you go through security.
Make sure you wear socks because US airports are weird and make you take your shoes off >.>
Bring a pen. When you fill out the customs thing, its a real pain trying to find one of the airport pens, they're always stolen. Plus if you have a pen, you can fill it out on the plane and then just breeze through.
When declaring things better safe than sorry. I always say yes to animal products and drugs. I generally have some form of leather clothes and birth control. They look at me weird and let me through, but if you don't declare and they decide to search...