Re: component wiring ?
I would personally run it the first way you said, with the component sets using only the front 2 channels because in order to run the tweeter and front speakers on 4 separate channels Im pretty sure you would need 4 separate crossovers, plus I think overall doing it this way it will be louder and most likely sound better.
when I ran Rear fill off HU power it just sounded kind of empty back there
Car: Chevy Cobalt Coupe
Front Stage: Mids: Aura rpm 4", Midbass: Four Aura NS6's
Rear Fill: Pioneer 6x9s
Amps: 2 Rockford Fosgate T400-4's, and a T1500-1BDCP
Electrical: Stock 140amp alt, Big 3, and a SHURiKEN SK-BT100
Winter sub setup: Kicker F12a IB mounted from rear deck
In the works: Diamond D9 12