Torque on a BB is not hugely specific, IIRC - you can judge it pretty easily with a wrench. (BBs are highly unlikely to come unthreaded regardless thanks to backwards threading on the left side.) Approximately 30 pound-feet should do it. Remember to use lots and lots and lots of grease.
The things you want to look for in a BB are as follows:
-Width. Some BBs are wider than others for various reasons. Most road bikes are (
AFAIK) 68mm.
-Threading. The two main varieties are Italian (right hand threading on both sides) and English (left hand threading on left side).
- Splines. There's four main types today - Campagnolo square, standard square, ISIS, and Octalink 2 (Octalink 1 is outdated and best avoided.) The latter 3 BBs look very similar, but are NOT compatible. If you want a Shimano crank, you need a Shimano BB , and vice versa.