Alright, so focusing on tasers:
I tried to find how exactly tasers damage the body, but I couldn't find hard numbers for it. I do know that tasers work by disrupting the nervous system. This can be done in two ways, one is that you simply force a current through the nerve cells which disrupts the signals going to the muscles and to the brain, which means that the muscles can not be temporarily controlled. The other way tasers work is that they send a signal similar to the one that comes from the brain through the nerves, this leads to the muscles contracting in rapid succession, and again immobilizes the person.
The permanent damage inflicted by tasers is mostly muscle tears and (I would guess) damage to the nervous system.
The tasers work with a high voltage but low ampere current, which allows the current to pass through weak insulators (like clothes). Jacking up the voltage might allow it to pass through things like leather armor too, though the effectiveness would probably be greatly reduced. (I couldn't find numbers on the resistivity of leather but I would guess that it is of the same order as of skin, which would imply that the effectiveness would be approximately halved)
Highly increasing the voltages here gives rise to electric arc discharges, which are essentially lightning, but going from one end of the taser to other, to complete the circuit.
This is probably not all of what you want to know, but I don't exactly know how to order all the other things in my brain.