A great resource for raised beds, particularly if you are starting small is:
http://www.squarefootgardening.com/
The soil mix used here worked great for us - as did the trellis.

For your environment (which is similiar to the climate we had the last summer we were in NC), tomatoes, squash, green beans, peppers and cukes would do well. Those are all the things that suffered here because it was such a short summer this year. You could do all this in one 4x4 space if you planned it out right. You would have plenty for eating, but likely not much for preservation/canning unless you happened to have a bumper crop. If you did SFG, you could also do succession planting and get spring crops, summer crops and fall crops from the same 4x4 space (particularly since you would have a long growing season). It's surprizingly less work than traditional 'row' gardening and it uses less water!