Frankly, I don't understand who's activating the bombs during scuttle anyways. If anything, it should require a minimum of one crew to scuttle (Which would tie in even better with the upcoming troop damage over time change). If you take out their crew before the scuttle completes, it should stop the process.
Nonsens because ships are instahulked in many situations. The counterpart of ramming/boarding spam tactics is scuttle, precisely.
The crew indicator refers to the operational level of the ship, not the crew itselve. "0" does not mean that there is not a single living member left, which would be unimaginable for ships that have about 60,000 crewmen, but not enough to run the ship.