(1) That sucks, survivors are trigger-happy on zombies for me. They don't seem to be a slight bit bothered by bandits though.
(2) Well lucky you, I only found two crashed helicopters, one having only some soda and the other inside of an unaccessible building.
(3) I don't think it's possible to make zombies target the AI without heavily modifying the DayZ code. I could be wrong though.
(4) I've had at least nine triggers.
(5) No idea, try shooting them?
DaiZy Single-player Developer (AI Units)