i don't know, since i don't grow grapes, but did you ck with the NC co-op site? they have lots of great advice on varieties and methods of growing stuff for this area. you could also ck in the edible landscaping forum, but since it's national, it may not do you as much good. good luck!

Generally and as I recall, there is a trade-off between planting to minimize erosion - across the slope - and to maximize sunlight, which in your case would seem to be almost down the slope (if my memory and spatial imagination are both working correctly), since you want the rows to run north/south so the sun hits both sides of the row in the AM AND in the PM. If there is a viticulture or grape-growing forum, you might ask there. There may be books available also - try your local library or inter-library loan.

I think your best bet would be to contact your local county extension agent and have him/her come out and take a look and advise you on the best siting. Seeing the site can give much better information than trying to visualize it. Look in the phone book under gov't offices, or google for your county's offices. If there isn't one for your county, then there may well be one for a neighboring county - they will usually cover both counties.