Yeah, you need to look up and understand "ampere-hours".
It'd just draw a huge current until a breaker blew (opened the circuit), which would deprive your load of the voltage that drives current through it.
Depends. You can have voltage regulation (can only supply up to so much current at a specified voltage), but they usually are designed to shut themselves down on a dead short. Current regulated supplies will just make your shorting wire get hot.
Whatever oscillator circuit you use will only be able to "process" so much current per cycle depending on its architecture and the specific devices it comprises; if it's capable of handling more than is available from the supply the output waveform will suffer, or it may oscillate irregularly or not at all.
You really want to design something like this backwards; first decide how much RF power you are willing to fool with which will narrow down your oscillator design possibilities, which will in turn narrow your power supply options considerably.
Mark L. Fergerson