Well, I can't help you on the lift kit, that is for sure, I am more for performance, which leads to lowering for better corners :wink:
As for HP, well, between me (I have had a few decent ideas, but by no means am I an expert), Mesenjaro (sorry If I butcher), DNYLRQ (right intials?), Andrew (if he ever appears on a regular basis), Drifter, and anyone else I forgot to mention (perhaps Mensa?), there are a few of us with knowledge on the subject.
The first thing you gotta do is figure out if any of your stock aprts are worn/failing/or eating way too much of your HP (for me it was the plug wires, through in some top of the line from Napa, and instant gain of a few, although I don't have a dyno, so I can't give you specs). The next step after that, is to figure out where the biggest flaws in the stock system are and improve them. Mesenjaro had great success by redoing the intake/exhaust systems. Of course, with all the wires he is running in that engine bay, it is hard to tell what exactly does what in there :wink:
Really, your best bet is to go through the forums and just read up on all the mods. If you want the ultimate power boost, try droppin a 3s-gte engine in there, or maybe being the first to do the V-6 that was recently proposed. Just a few ideas. Most of all, just read the boards, post with questions, and best of all, post with ideas so we can agree, point out faults (and possible fixes), or just totally decide that it is idiotic, and ignore you forever because of that. Actually, we will prolly just tell you taht it is a bad idea and steer you in another direction.
As far as off-roading goes (your purpose I am assuming from the idea of lift), I don't know who on here has done that much. I know I took mine off road a few times, and basically stock she does just fine on the rocks and such.
Welcome to the boards, and we look forward to seeing your Rav as it grows into its full beauty.