Voltage gauge pegged - how to find short

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 ?

I'd start by checking the under-dash grounds. Poor grounds always result in strange, multiple problem, indications.

Check the voltage at the gauge it could just be a bad gauge?

Gauge fault on the volt meter for sure....check voltage across the terminals of the volt meter and compare.
Fuel gauges are notoriously inaccurate and fluctuate when moving along. What happens when the tank is full, does it still do it?