New to truggys

Hey, my dad and I race with our t4s and xxx-ts( the t4 being mine and the losi being his)But we want something bigger, but not quite emaxx big, just a tad smaller, and I was thinking... ahha! TRUGGY!Soooo im really new to rc only being in it for a couple months and need a couple questions answered if you would.

1.Are most truggys 4wd?
2.Whats a good truggy setup for racing and minimal bashing?
3.what are some basic upgrades for a racing truggy setup?
4. do the truggys have 2 gears like the maxx?
5.whats a slipperential?
6.Anything I should know about truggys being practically brand new to rc?
7.Are they as hard as they look to maintain and learn parts and stuff on them?
8.Sorry for so many questions:002: ,Caine