Hi, have owned my 2003 1.8 20v se for nearly five years. Could somebody shed some light on the following two problems?

1. The car started locking me out last week - whilst engine running if i shut the boot! This would not happen if any other door was still open. Had to call out breakdown company to get me back in. Then, the car would be driving along and all of a sudden, the alarm would activate, hazards and horns whilst driving.
Please, any idea what the cause may be? Also, how to fix it if simple diy. If not am i best off going to an auto electrician? Don't fancy going back to Seat as i think it will cost a lot. Grateful for any advice.
2. Rain water collects in both front door jams at the bottom of the rubber seal. It rises up over the plastic door covering, seeps through and runs into the back of the car, soaking the rear footwells. Cleaning does no good. Any other solution? Grateful.