Basically, does it work? They do have a LD rating, but that usually comes from the crew. I don't see why it wouldn't work, but since the wounds are usually resolved against the chariot itself I'm unsure, since the machine itself doesn't have a LD rating.
I don't see why not. Chariots are considered as a whole much like cavalry, so you cannot just kill the mounts and/or the crew. The combined stat line represents a certain level of abstraction. I would think of the failed Leadership check as the death of the crew and mounts together. That effectively 'kills' the chariot just as well as splintering the actual chariot itself.
Yeah it would work, anything like drain soul or things that could only affect living enemies still work on chariots because it can effect the crew and steeds. Remember though, if you use it on a character on chariot it would kill one or the other, depending on what you targeted, not both.