Dinny, check out the WeGotServed website. They have a nice (but not free guide) to the built-in Lion server. It probably does most, if not all, of what you need. I'm sure ML server will be pretty similar.
Yep, I only have Lion on the air. Everything else is Snow Leopard. I'll probably upgrade the air and keep everything else the same. Now for the real decision. New iPad 3 or new Air.