Advice on optimizing a biamped system

Hello!  I am a noob to this site, and am getting ready to do a relatively large install.  In reading through posts I have been completely impressed with the level of knowledge on this site.  Before I get started on the install, I would like to hear some opinions about this system and how you would change/optimize what I'm trying to do for this biamped system in a 2001 Jeep Cherokee. 

Over the years, I've picked up gear here and there, and I am looking to build a clean, good-sounding system that can rock when I want it to.  It's not going to be top audiophile quality, but I think will sound pretty good.  I listen to just about everything, so huge bass and SPL levels are not my goal.  For speaker placement, I have a set of Q-forms I plan on using, with some beefing up increase their stiffness.  I would have built my own, but I'm horrible with fiberglass.  The rears will go in the soundbar.  As for the hardware, my main components are:

Alpine CDA-7845 head unit
Alpine 12 disc changer

Infinity Kappa 60.5 components (front)
Infinity Kappa 52.5 drivers (rear)
Infinity Perfect 10 sub (sealed box)

Sony XEC-1000 Active Crossover
 (3 sets of RCA inputs, and outputs for the sub, front high and mid, and rear high and mid)
 (18db/octave crossover for the sub, 12db/octave for the rest)

Alpine V12 MRV-T500 2 channel amp (bridged at 4 ohms for the sub)
Alpine V12 MRV-T500 2 channel amp (running front 6.5" component woofers)
RF Punch 100 2 channel amp (running front tweeters)
Alpine V12 MRV-F250 4 channel amp (running rear 5.25" speakers)

My immediate questions:
With biamping, I'm not planning on using the Infinity passive crossovers on the components at all, just the Sony XEC-1000.  Should I use the crossovers on the amps in addition to the active crossover to get a greater slope?
As to using the F250 4 channel amp on the rears--should I bridge the output for more power and use the Infinity passive crossover, or should I ditch the Infinity crossover and run 2 channels to the woofers and 2 channels to the tweeters?  They're really more for rear fill than anything. 
Someday I would love to get the Audiocontrol DQXS to replace the Sony crossover.  Would that be the best use of my $$$ for a noticeable upgrade?

I'm pretty much going to stick with most of the hardware I have, but any advice on how to optimize this stuff would be great.  Thanks for your thoughts!

Keep in mind that the crossovers are what give the component speakers their voice.  You can't use an active crossover in the place of a passive crossover and expect the same results, even if you could match the slope and frequency used in the passive crossover.  This is because the passive crossover is "voiced" for those speakers.  I'd recommend using the passive crossovers and not bi-amping unless the crossovers are designed for it.

As for the rear speakers, I personally don't like them.  Music is stereo, which is designed for front left and right speakers.  Providing extra sources like that will have negative effects on the soundstage and imaging. 

Steven Kephart

Adire Audio

Thanks!  I guess KISS really is a good idea . . .

I'll go with the passive crossovers and see how they sound.  Should I run the Sony crossover on the input level for basic high/low pass functions, or ditch it and just use the crossovers installed in the amps?  

The responses were excellent--thanks for making your advice so clear.