There were numerous threads on these on the old board, but the basics are;
Belt tension. If you haven't got a tension meter, and I'm guessing you haven't, the tension is correct when you have got about 3 or 4mm belt deflection on the run between the cam pulleys using "moderate" finger pressure.
Another "trick" is the twist method. You should be just about able to twist the belt 45 degrees, although IMO this is less accurate.
The alternator nut was a gremlin that affected pre '99 bikes mostly. The quality of the nut wasn't very good and it unscrewed itself. This let the flywheel come adrift and could cause all sorts of damage, from minor scuffing to wiping out the crank.
There is a new design of nut now that is supposed to prevent this happening??
It doesn't, but is no where near as common.
Buy a Haynes, and check how to check/do the jobs. They're not too hard with a bit of common sense