I'm making a trip soon to Guitar Center (its miles away from here) and I really need to replace my preamp and other tubes in my amp because they're starting to crackle and I always wanted to do away with the stock tubes.

Does anyone know of exactly what I would need?
Changing to a different brand of tubes really won't make that much of a difference. If you have a manual for your amp it'll tell you exactly what you need.
ESP LTD EC-256 and a Fender Deluxe VM
check the "everything you wanted to know about tubes" sticky.

then check out http://www.tubedepot.com/ or http://thetubestore.com/ or http://www.eurotubes.com/ for what you need instead of GC, GC usually has a very limited selection of tubes to choose from and it will save you some gas not having to go there
My Gear:
Schecter C-1 Plus with EMG 81/85(18v mod)
PRS Tremonti SE
Randall V2
Genz Benz G-Flex 212
BBE 482i Sonic Maximizer
ISP Decimator Prorack G