TMB

Could be a wheel bearing. Is it a whining/moaning sound?

The muck and sludge from the scuttle panel drains ends up trapped behind the bottom of the wings. That's what rots them out. Mine are starting to go. Not had experience of fitting any panels on it yet though.

Yep

Nah, it works the other way around. The switch is not being pushed when the door is closed. When the door is opened the switch is pushed by the lock cam and the circuit is closed.

Don't know. The diagram is not detailed enough.

Yes, the interior light microswitches are on the outside of the lock module. They are held on with a metal clip. All other microswitches are inside the unit.

Mine's only a base model Fabia but the back doors do work the interior light.

Hmmm, I guess you coud pull off the plugs in the rubber door bellows and see if the light goes out.

I think I was mistaken about the convenience unit. I think the relay is actually inside the Onboard Supply Control Unit (J519) above the accelerator pedal. That is a different module to the convenience unit.

Unfortunately I don't. Someone else may be able to help though.

Sorry, just realised you were asking where the convenience unit Onboard Supply Control Unit (J519) is. It's under the dash above the accelerator pedal. However, if the relay is faulty if can't be replaced unless you open the module and solder a new one in. Not an easy job at all. You can replace the whole unit but they have to be coded to the car as far as I know.

There is an interior light wiring diagram in amongst these... http://inhouse.uw.hu/elektronika/Skoda_Fabia_Praktik_1.9_SDi_2006_wiring.pdf

Only beeps with the drivers door. Here's a video....

Yes the interior light switch is a microswitch on the drivers door lock module inside the door. If those other functions are working though, it might be the relay in the convenience unit Onboard Supply Control Unit (J519) which controls the light.