I have the PAC adapter, it works well. I have it setup to adjust volume, channel, source, and the power button is mute. Of course, you can program it to do whatever you like. My only gripe is the channel up/down won't control presets.
I currently have my GPS antenna under the dash, actually it's on top of the AVIC. It gets good reception there so I don't plan on going through the trouble of mounting it outside. The XM antenna, for now, is running out to the roof through the front passenger door. I plan on running it through the third brake light when I get the chance. I tried to wh