I am so confused on some of this stuff. I have an 07 LTZ, no nav or rear entertainment. I wanna add both, I was considering buying the DNX 8120 for the front and then just a 10'' flip down. Could somebody guide me to what adapters I need to keep the all the factory stuff going ie OnStar, Bose, XM...The 8120 also is capable of doing xm traffic, more adapters/antenna or is it all there already since I have XM...