when you start the car the brake light indicator should come on in the check control panel. this is by design. when you depress the brake pedal it should go away.
i am not quite sure i am understanding the issues you are having with the door locks. but i will let you know how mine work.
the driver side door lock can lock and unlock the entire car, including the trunk. it also features a double lock. this is activated when the keyhole is horizontal. when this is activated only the driver side door can deactivate it. you can unlock the other doors on the passenger side and trunk but the driver side will remain locked. if while double lock is engaged and you unlocked through the pass or trunk, then lock thru the pass or trunk, it will lock all unlocked doors and driver door remains locked.
if the drivers side door is not double locked then they all do the same thing when locking or unlocking. if not double locked and you unlock from any keyhole then all doors will lock, if locking through any keyhole then all doors will lock.
not sure about the pressure wash question. . .
hope this helps!