www.obesityhelp.com is a good website. There is a lot of information there.
As far as protein drinks go, you need to check out the food forum under protein drinks. There are places you can order samples. It's best to do samples until you settle on something you like. Most people end up liking something after surgery, than they liked before surgery so it's best not to stock up on a lot of anything.
It depends on your BMI on whether or not you will have to drink them pre-op or for how long. You will definitely need them after surgery.
If you have a costco, the Premier protein drinks seem to be something everyone agrees on and is extremely popular.