I finally got my Terraflex 2.5" BB installed!

But I have alot more I want to do. So I have a few questions.

I've been looking at alot of the pic threads on the site..and thanks to everyone who posts pics. I'm completely stoked...

I'm shooting for 35's. I don't do a whole lot of rock climbing or mudding...but I live in Colorado and spend most of my time above 9000ft off road camping, snowmobiling, skiing, etc. I require 4wd and good traction and the truck is also my Daily Driver. (I have a 2001 Chevy 2500 with an 8.1L that gets about 8MPG To me this thing is a Prius on fuel!)

I have the Sahara 18" wheels. I actually like the wheels...but not so crazy about the shiny almost chrome like finish. So I'm kinda thinking professionaly painted or powder-coated. (I'm a DIYer but pretty sure I want a PRO painting anything on my JK.)

Ok..so my questions are:
What size of tires can I fit on the 18" stock rims?
I believe the terraflex site says I will need spacers, but what about the wheel on the rear gate?
Do I need a spacer for that rear tire, will the size of tire even fit back there? What about the rear center tail-light will the tire cover it?
If I get 18" tires and decide I am unhappy with the rims..what are the chances the tires I bought fit on aftermarket 18's? I have a feeling this has something to do with backspacing...still reading up on that one.
What are some good websites to look at wheels on?

Thanks...in advance for any advice or answers. Other than my 01 Chevy I've always leased vehicles since I was 16, so never really had the opportunity to mod.