RE: Defrost on all settings. Check for a blown fuse, #14 I think. ACC system uses two fuses as I recall and when the one blows, the car goes into fail-safe mode which is defrost. Mine used to blow the fuse every time I floored it. Turned out to be the wire for the transmission kick down solenoid. Wire had worn through and shorted under the trany support.
Water in trunk means leak up high. my back window leaks. Gotta get the glass shop to pop the windeo and redo the seal. And probably fix some rust.
Slow shut off can be a weak vacumm pump or a leak in the vacumm system somewhere. I would probably isolate the locking system and see if it shuts off ok. sounds like a leak in lock system line. probably at the door with the problem.