Gas freezes, or at least turns into a slushy so you cant drive, you have to have a 1/2 tank of gas up here or it will slushy and you cant get home from work lol
He is getting a medusa 1600 v2 60mm motor from me. 5-6 lipo will be fine with that motor. If you plan to race 4s lipo with s larger pinion will work too.
Stick with the center diff or the tranny. Direct to diff outrunner setups require more experience to do right. Good to get a few std style conversions under your belt before trying!
As far as lipos... I prefer a single pack if possible, but you can run a pair of packs if it fits the vehicle better.