Sorry for the delay in responses.

The GPS and XM antennas are actually in the front window at the far passenger side. You can't see it from inside but I'm not overly pleased with the way the XM will 'fuzz' out occasionally. On my 2002 I had the Delphi SkyFi 2 with an externally mounted antenna and I would *never* lose reception. I notice this is a little more susceptable to heavy tree coverage.
The GPS receiver is fine there however.. It's a really smart system it uses a 'pulse' on the wiring of your vehicle (don't ask me I don't know how it works) even when I drive in a long tunnel, the mapping doesn't miss a beat. (there is some mild assumption you are still on the road however but I am very very impressed having used GPS software for ages)
After using it a while a couple things I have noticed:
1) To bypass the lockout, simply flick your lights once when you see the "loading..." text a few seconds after you turn on the ignition... Just turn them on and off quickly (not flashing your highbeams but actually turn on and off).
2) The system is a little sluggish sometimes, and I think for all its 'power' it changes stations on the XM incredibly slow. I understand it will take a moment to get the channels reception in but I mean just going up 2 channels means: [up] (wait 2 seconds) [up]. Kinda annoying but I've gotten used to it.
3) If you add in your commonly used addresses and give them a voice tag, you can hit a button and just say where your going, and boom you're routed. Spiffy.
Anyone had any luck on finding an adapter?