1990 Supra Conbrio

I have some electrical issues. First, the voltage gauge needle is pegged all the way CW when power is on...so there has to be a short somewhere. So where is the best place to start looking for that?

Also, there sometimes is a semi-buzzing sound coming out of the dash....like an alarm wants to sound but doesn't quite have the juice! Could this be part of the same short?

Finally, the fuel gauge, which itself is not accurate, goes to complete empty at high RPM. Where do I start with that ?