Todd -
Probably one of the frame builders on the list should properly take this question but I'll jump in.
Relaxed frame geometry can be found on a touring bike, 72 degree head and seat tube angles, wheelbase of 41.5 inches and a longish fork rake would give you a stable, straight ahead ride. A frame with "criterium" geometry would have 74 degree angles, 39.5 inch wheel base and a reduced fork rake ("straighter"). Such a bike would feel very responsive, dive into corners, and perhaps be a bit "nervous" in a straight line.
Look at a couple bikes you know and then ride them to get a feel for what small changes in the frame geometry can do to riding. This is the essence of the framebuilder's skill I think.
As for your 2nd question, unless you have a complete shop and are very familiar with fabrication, you are probably wasting your time trying to teach yourself framebuilding. Along with design of the frame, you'll need to learn about measurement and mitering tubes, proper brazing techniques, and how to file / finish your frame so that it looks presentable. Without the help of a skilled instructor such as those at UBI in Ashland, the chances of getting it right on the first try, in your garage, is pretty small. Suggest you start by purchasing the Paterek manual and read it cover to cover, a couple times, till you understand everything in it. Then get a couple junker or crashed lugged frames from goodwill store or bikeshop, cut them up to see how the head lugs and bottom brackets are done, and try to miter and braze some tubes together to develop a semblance of technique.
There might be a builder in your area that you could buy lunch for - but your signoff did not indicate where you're located.
Good luck
Mark Petry
Pouring rain on
Bainbridge Island, WA