2005 chrysler pacifica limited awd

I just bought an '05 pacifica limited AWD.  I would like to upgrade the amp, speakers and sub. The factory systm has the 6 disc dvd changer and single disc dvd both in dash, rear flip down monitor with wireless headsets and remote, U-Connect controlled through the stereo and in dash dvd navigation.  I would like to be able keep all of that, so replacing the head unit is pretty much out of the question.  What I'd like to know is can I reuse the factory wires from the deck to the amp and from the new amp to the new speakers and sub?  I plan on running new power/ground for the amp just because I've had bad experiences with other peoples power wires and won't make that mistake again.  Im also curious as to whether all 7 (I think) speakers and the sub are amplified or do they come straight from the deck? Sadly I haven't even dug the factory amp out yet so I don't even know what I'm getting myself into here.  Is there any chance I'll get RCA pre-outs out of the factory deck?  Whats going to be my best bet for amp/s? Two 4-channels?  Any insights, advice, warnings, suggestions, ideas,  etc. would be appreciated. 

The OEM radio does not seem to output through shielded RCA cables. To get you started take a look at the following: Entertainment system diagrams