'94 Camry Security System

Got the car with the key fob transmitter, what looks like an aftermarket security sytem that I am lead to believe the dealers were installing, has the little silver switch and brain box under the dash, speaker and motion sensor mounted on the fire wall. I just don't understand how this system works. What function does the under dash switch have? It doesn't seem to matter what positon it is, the horn still goes off if I arm the system and then open a door. How can I get this system to just open the doors remotely and not have the freakin horn go off all the time?

Second question. About 5 seconds after I start the car, the doors all lock. I have another 94 Camry (didn't get the key fob tx, so I just deactivated the alarm) and the doors do not auto lock. I have managed to lock myself out of this thing twice now (luclily a door was ajar both times). I REALLY want to deactivate that system, and am curious why my other 94 never did it. Caught me off guard. Thanks for the help. This is a great board.
FABB

Never locked myself out of the car so not sure how that works ( and I also have the auto locking doors).
Far as the switch under the dash - that's only for programming a new remote - turn on the ignition and flip that switch a programmed number of times to get the alarm system to recognize a new remote activator.