Vauxhall Astra multiple electrical issues

Hi

The central locking on the passenger side door is on and off. sometimes it locks all doors except the front passenger door.

a couple weeks ago, the driver side back indicator light was constantly on, not flashing, but just illuminated. even when the car is off and the key taken out the ignition. I tried taking out the fuses to find the one linked to it. turns out the fuse for the aux power supply seems to be powering it. when i remove that fuse, the light goes off, but then doesn't work at all rven from its assigned fuse.

the windscreen washer pump as well stoped working, the fuse is fine, so clueless as to what to check next

the biggest of them all was today, i parked the car and went shopping. when i came back, the horn was constantly on, when i pressed the fob to unlock, it stopped, but while driving it went on again constantly, i ended up having to pull over and remove the fuse. but even with the fuse off, i can hear the electrical humming, which i only assume, if the fuse was in, would be setting off the horn.

any advice and/or help would be much appreciated