If I put a fork in the electric socket do I get all the power plants and water dams power?

nope. you might get the full 110Vx20amps (if a 20 amp circuit), or even a larger current pulse very briefly. that is hardly a drop in the bucket to the output of a regional power plant. the most you can get depends on the capacity of the line from the nearest transformer (presuming all the downstream lines have a much higher capacity for current than the transformer can put out). Most household wiring is rated to much lower current fluxes but if you get hit by something that would melt wires and insulation, well, it would suck to be you.

Transformers don't have infinite output capacity, so whatever max load that transformer puts out is the maximum you could ever get, and you wouldn't even get that because there are other users being supplied from the same limited source, even if there were not other reasons that the load to that outlet will be limited (and there are those reasons).

Nope. There are fuses and other security-measures to prevent that.

You may get a nasty electrical shock from the short-circuit

not from a wall socket, you get it from a toaster and a nice bubble bath