I run the Tera short arm (3 1/2") kit. It rides as well or better than it did stock, I can't imagine the 2 1/2" kit being any different. Also, I wouldn't waste the money on a long arm kit, especially with 2 1/2" inces of lift.
I have the RSE's on mine, and have nothing but good to say about them. I really like how they're about the same width as your flare, keeps most of the crap off the side of your Jeep.
As far as bumpers, that's a decision only you can make. Like you said, a bazilloin choces and they all serve...
You have to anchor it to the concrete to use it at all, which is one reason I won't be using it again (I aint about to drill through my purdy new floor).
If you want it, you can have it.
Yeah those work for 35's, that's as big as I've ever tried. I'll let mine go cheap if you're seriously looking, I'll never use it again (knock on wood). I was using it a lot with the old style MTR sidewalls. :D
It wont. I'm at 2700ish rpm at 75 mph. If anything, I wish I was lower. Like you, I went from 4.10's and 35's to 37's and 5.38's. Zero change in the mileage, it'll always be kinda crappy, HUGE increase in performance though.
Not to sound like an old fart or anything, but that "Arch" wasn't even there the first few times I ran it. Oh, and it's a fallen tower you have to drive under, not an arch at all.