Yes they are under the destructables section, but you have to each "enable" or "disbale" them. I think when they are enabled, they are close, and disabled are open, i could be wrong on that one though.
As for your vehicle question, you may have to do a trigger which replaces the unit with another unit. Like you can say
Unit Enter vehicle1
replace vehicle1 with vehicle2
just make vehicle2 be able to move and and have all your attack damage you want on that
and make vehicle1 not movable w/ no attacks
Then for exitiing you can say
Unit unloads vechile2
replace vehicle2 with vehicle1
this is just the basic conept of the trigger, there are other things that would have to be included. but that should get you started