You've got a bunch o' issues there!
Camshaft - under the engine cover, disconnect the N205 VVT solenoid control valve. Start the car up with VCDS hooked up and monitor measuring block 93. This is the cam phase angle, which in English means information the ECU needs in order to inject fuel precisely at the right time. You need to see between 0KW and -3KW. If it's a larger number, the fault code is correct - the timing is out a tooth. Very common problem. Some mechanics seem to struggle with engine timing......they have one job to do.....lol
The timing could be out on the cambelt, or the chain, so both need to be checked.
Numerous electric gremlins - Sounds to me like you have a broken wire or two in a door harness, possibly the driver's door, or the rear one as it hints at.
Alarm - Common one that. Replacing the siren module usually sorts that.
Slow revs and lack of power - More than likely a failed front PCV valve, which again is common.
Definitely worth bothering with mate. None of that is particularly challenging but the alarm module (from VAG) isn't cheap and labour to restore the cam timing won't be cheap either, but it's certainly not worth putting the car in the bin over
