If you decide to go with powder coating, I highly recommend Miller's in the Lilburn area:
Miller?s Powder Coating
These guys did some motorcycle wheels and a few other parts for me, and were excellent and reasonably priced. My motorcycle wheels had a lot of small nooks and crannies where the brake discs attached, but the coating is very complete and uniform.
Good luck.
Some additional thoughts on your post: In my experience there is no need to be concerned over after market wheels. I have a set of OZ Allegerita's in what they call anthracite black that are excellent, quite low weight, and a bit wider than stock.
For new tires, I suggest going to see Kirin at Gran Turismo East.