2006 chrysler 300c, avh-p4900dvd

ok yes i am a newbie. yes i did use the search feature but i am looking for a vehicle specific answers. this is what i am doing.

i have a 2006 Chrysler 300C with factory non navigation HU,but has the boston acustic system, and steering wheel controls.

now i am getting ready to purchase the pioneer AVH-P4900DVD, a db drive 1000 watt amp and a 12" db drive sub. but here is my questions. will i have any issues running the factory speakers/ amp with the pioneer? what interface do i need for the pioneer to work with my steering wheel controls, and how hard will it be to run a set of headrest monitors off of the pioneer?

Just will have to trigger the factory amp, and also the new amp with the blue remote on the Pioneer.  For the steering wheel controls, look at pac-audio.com, more specifically, the SWI-X i believe.  The Pioneer has a video out, so you will have to split the vido signal between the two.