I figured out the last bit about tension a day ago by trial and error. The high limit screw is barely in(just enough that I don't lose it). The bike now can shift without clanking or the chain from falling off except in one gear combination. If its in the big ring in the front and highest(biggest diameter) cassette in the back, the chain will fall off every time and very easily. I'm afraid to mess with the limit screws too much, they're getting kind of stripped.