I just bought my dream car, a 2004 Audi S4. It has the optional Bose stereo, which, in my opinion sounds like doodoo. I want to keep the factory head unit and replace all the speakers in the car and factory amp.

This is how the factory Bose is set up: 4 pre-outs from the head, a separate 215 watt amp powering separates in all four doors (6.5" woofer and 1 1/2" tweeter), a four inch center channel in the dash and a 9" NID (?) sub in the rear of the car... 10 speakers in all. I'd like to install the Dynaudio 240 GT speakers (6.5" woofer and 1" tweeter) and possibly a Dynaudio 10" sub. But here's where my questions begin:

1. Should I put separates in all four doors like they have from the factory? 2. Can I still use the factory head unit? If so, what do I need to do to use it?
3. The factory 9" sub is extremely flat. Can I fit a 10" in the factory location or would I be better off using an 8" sub?
4. Once all these questions are answered... What amplifier, brand and wattage, should I use to power all these speakers?
5. Does anyone know of a dealer or store in Pennsylvania near Philly where I can buy these speakers and get someone to do the install? 6. Is this going to be a difficult job? And what can I expect to pay?

I appreciate your help........