I would pull the belt off and inspect all of the pullies. The best way to take that tensioner out is to remove the engine brace and jack the engine up slightly. I think there's 2 13mm bolts that keeps it together.

As far as the electrical problems go, I was thinking more on the lines that you have a short somewhere, possibly in or near the fuse box. I've seen on some cars (Ford Contour just to name a name) where battery corrosion would eat away at some of the power wires, namely the main one that went to the alternator and fuse block. I wouldn't hurt to check the alternator too.