I don't see a bike co-op in Louisville; too bad, that would be helpful.

Start here: http://www.sheldonbrown.com/frame-sizing.html

Actually it's worth your while to spend some time perusing sheldonbrown.com. Most people consider Sheldon (RIP) to be THE source for all things bicycle.

On any older bike you buy, you'll want to know if the bearings have been repacked. If they have not, that will need to be done. You can DIY but it takes a few tools; helps if you get to know someone local to teach you a bit and loan some tools. Otherwise it's the LBS and a few more dollars. Heck, maybe the seller is your guy for startup help.