Chain tension is really all you have to worry about, and it's not too hard to get it right. Just fart around with it and you'll see. Like humancongereel said, about 1/2" of vertical chain movement is good. Too tight, and you can mess up the bearings in your BB, too loose and you might drop your chain (keep a brake on your bike?).
Really, changing a flat on a FG/SS is easier & faster, since you don't have to mess with derailleurs or extra-long chains.
Wheel centering is easy; you already have the tools (mounted on the front of your face, just beneath your forehead and above your nose).