what capability the Arduino has as far as monitoring voltage
A 10 bit A/D converter. It has 6 inputs that can be switched in turn to this converter. The input voltage can be up to 5V but no more. The reference voltage is set at 5V but can be switched to 1.1V
and amperage levels
No capability at all, very little in electronics has. You convert a current into a voltage by passing it through a resistor and then measure the voltage.
and controlling capacitor banks.
No capability at all. But it can control relays and other digital outputs that can be connected to equipment that can control capacitor banks.
Is there an existing or standardized setup for variable power output
There are many ways of controlling power but it depends on what you mean by that phrase.