1. There are several good mechanics in the area. I use Truett Ray at Shadetree Garage. He has experience with M cars and is a great guy. Johnson and Johnson in the area is also very good, there are others as well. In Greensboro, an hour away, is Kormann if you need very high end work.
2. This winter was worse than usual. Usually 5-6 days per winter with snow/ice on the roads. I don't drive my m6 much in the winter because I have other options.
3. don't know. I expect they would be cheaper here. May want to try autotrader etc. and see.
5. Join the Tar Heel BMWCCA chapter