Number one: Common issue with the rear cluster for the number plate lights, we have this issue with our E46 330i Sport. Try a new bulb, try cleaning the terminals, failing that, take it apart and check the wiring on the back, check the wiring where the cables go from the car to the boot, if all else fails, buy a known working rear cluster (around £40 on ebay)

Number 2: Clicking is a sign of the battery being flat and not enough grunt to turn the starter... Could be a couple things in my eyes, starter is on its last legs, battery is flat or old and passed its best.... or another thing to try, give the terminals another turn on the battery... Had a simular issue before and this worked, was not tight enough and causing all kinds of electrical issues.

Number 3: Oil light staying on is telling you the oil is low, worry if it comes on when your driving... They have been known to throw a sensor and cause the lights to come on, replacement from BMW is not massive money, check your levels first though to make sure that is not the case.

Check earths, electrical issues can be caused by poor earth straps... Failing that, get it on the diagnostic machines... I know a good BMW specialist in Yeovil if your in shit