Onstar Compatible with XM or DVD Players

[prplprowlr]

I know these questions has probably been asked before but I coulnd't find the answer I wanted. I have a few and want to make sure I get them right.
1.If I add an aftermarket radio I know the steering wheel controls are no longer useful unless you get the device to make it work but does it affect onstar?
2.If I add the DVD/Headrest kit from SMA does it affect my steering wheels controls or onstar?
3.If I decide to add Just the Pioneer XM Radion that uses the FM Modulator will that affect my steering wheel controls or onstar?
I know these are lots of questions but I know several of you out there of helping me answer these questions. I really want to add some aftermarket items but don't want to lose some of the factory options. I am really leaning towards the headrest monitors and the XM Radion adapter and was hoping it would not affect Onstar or Steering Controls.
Thanks Guys
4. Just thought of one more question. I thought about moving my Onstar unit somewhere else and wanted to know how hard it was. I was thinking of mounting my xm radion unit there or a flip out dvd screen.

[This message was edited by prplprowlr on 07-27-03 at 01:54 PM.]