I have the 6610 in my 2005 DC 4X4 Limited as well, but I dont have the factory rear entertainment( I have rear headrest monitors w/IR headphones). The steering wheel controls are plug and play with the 6600/6610. There is a harness that bypasses the factory jbl amp that is plug and play also, but I dont know how it works with the oem dvd player, or if it will work at all. Sorry I cant answer the last.

I hope it will work for you, the 6600/6610 is an great HU and would recommend it.