I'm sure of an answer for 1 and 2. 3. Alot of players believe the generator loses health on its own, but that is actually not the case. The further you advance in waves, the stronger and more accurate the faction enemy bots are. As soon as they come out they are already shooting while still running and hitting their target. Even when you think you are doing all you can, the enemies are coming from all sides, so while you maybe turned to the left shooting an enemy, another maybe coming from the right getting a couple of shots in before you turn to shoot it.