first off why are running 1.5" wheel spacers if you are bone stock?
ircc 4.5" of backspace is the same as -12mm offset.
"thinking of getting the XD Hoss"
1. try discount tire.
2. with 35's you might need to cut/trim your fenders or run flat fenders
3. no your tires would stick out way past the fender
4. i run 37X13.5xr17 toyo mts on 17x9 XD addicts
"teraflex 1251000 Suspension 2.5 lift OR the Rubicon Express 3.5"
i don't know much about RE but teraflex is a good solid brand. i run a rock krawler 3.5 max travel
1.yes depending on your wrenching ability
3. which kit is more complete
4. if you go for a lift kit you don't need the leveling kit, the lift will take care of the rake. it would be redundant
5. yes you will end up messing up the tailgate.
remember also that when you go up you need to look at extending your diff/tranny breathers, BRAKE lines. with 2.5 your driveshaft should be OK but you want to upgrade them if you 3.5+. i still run my stock ones for now but they are on the short list for my next upgrade.
you will also want to think about beefing up your front axle. truss or sleeve, gusset the C's at a min. ball joints maybe even knuckles.
and with that 3.8 don't forget about doing a re-gear at some point.
hoe my ramble helps....