Upgrading Stereo - Active?

[ard]

hi all, i recently picked up a touring Z without nav. i'm going to be going with a single din head unit, i ordered the alpine hd149bt

i have the following amps from the stereo in my previous car:
RF T400-4 and an RF T500-1bd that used to power a 10w6v2

i'm looking to sell my existing sub and i'm going to be picking up the JL stealthbox (purely based on aesthetics) that i believe will have two 10w3's. first question is will my T500-1bd be ok to power these subs?

as far as powering the speakers, i've noticed a couple people promoting not using rear speakers. this is the first i've heard of this but i'm willing to give it a shot. if i do that i do have a 4 channel amp... does that mean i can go "active" with one channel per driver? and just because i can, should i? i would need an audison bitone or something to do that right? i admit that i have trouble maximizing the audio quality using a full parametric eq. i'm not so good at tuning but i know good sound (to me) when i hear it.

on to speakers, i guess i can fit 6.5's up front. could i get some recommendations? i can tell you that in my previous car i put focal 165 k2p's in the front and i never really liked them. i had polk db6501's in the back and honesty i always thought those sounded better than the focals. what does that tell you? I'd like to get great speakers but i'm afraid that great speakers might just not sound good with mp3/aac music which is primarily what i listen to. Even before the 165 k2p's I had a fairly expensive set of focal 3ways that I didn't like either. They sounded great in the store but crap in my car. So you'd say oh they need to breakin...well to me they never did.

lastly, if i get z enclosures speaker rings, how do i determine what size opening do i want to get the speaker rings in? same question for the tweeter adapters, what size opening?

thanks for reading!