I'll try to answer some questions for you.
Now the questions:
1. The shark fin XM antenna. Is there an adapter that would allow you to use that or would you have to run a different antenna? (Such as this
http://www.myradiostore.com/antennas...gm-single.html)
2. The factory microphone. Can you use that? It seems as though you have to use the one that comes with the radio. How big are those generally? Best place to put them?
3. You can't control the Onstar volume except with the sterring wheel controls correct?
4. Are there any other little quirks or gotchas?
5. Recommendations for the best prices? Crutchfield only seems to have the Alpine kit which is a little more than I wanted to spend but some ideas on what works best would be awesome. DoubleD Mods seems to have a good selection as well along with all the required parts (I think).
With any radio you my have to buy an XM adapter for the XM radio to work.
1 yes that will work with the Camaro XM antenna but you will loose signal strength. It is not as strong as the XM antenna.
2 I have not read about any one using the onstar microphone. They are about 3/8 in diameter and about 1 in long. I have mine next to the rear view mirror.
3. No you can not control the Onstar volume using the radio just the steering wheel control.
Google the radio you want to buy and you will find a lot of places that are cheaper the Crutchfeild.
When you buy the Scoshe/Alpine dash kit make sure it has the newest software and firmware. The old software and firmware the steering controls did work allong with some other problems.