Thanks for the info on the Delphi Roady2; I'll have to check that out.
If you can help it don't use the FM transmitter (Universal Audio adapter) it degrades the sound, the cassette adapter is a bit better but the best choice is a head unit with the XM reciever built in. Be aware that the voice channels are reduced bandwidth which is conserved for the music channels. The music varies in quality depending on the source of course and also when it was digitized, the newer codecs are better giving near CD or full MP3 quality to some not much better than a low bandwidth stream but for the most part it still sounds better than FM except possibly some stations in the college band using good broadcasting techniques and equipment. Sometimes you will hear compression artifacts.
They have all the manuals online for research here.
http://www.xmradio.com/manuals/manuals.html
As for reception at home which of course is different than a car I get full lock on both satellites and a terrestrial transmitter. I don't have it in my car but I understand there are some dropouts in cities with tall buildings and under bridges. It is an either or proposition it either drops out or you get it.