1. Yes, setFuel 0. Depending on the vehicle, it is sometimes possible to use the damage slider to put the vehicle into a state where it is possible to get in, but the vehicle won't move. Experiment.
2. Dunno, try removeWeapon. You can certainly take away the ammo with the slider or removeMagazines commands.
3. A stronghold is a fort, castle, defended base or fortified position..... anything like that really, it's a very general term. It can even be a large area: "The last stronghold of the Resistance was the mountains in the north of Nogova."