Do the rear swivelling reading lights work? I suspect not, since these are turned on by the button(s) that you mentioned. It would be unusual to have all four bulbs blown (the two 'door' lights + the two reading lights). But maybe they have just failed one-by-one over the years. Perhaps check for voltage at the light fittings.
What about the buttons on the rear view mirror console - they let you turn on the rear 'door' lights separately from the front lights - any effect? I think sunroof-equipped cars are missing those buttons.
Somewhere in the system (under the glovebox, from memory) there will be a large (long) white 'relay', which is a delayed switch-off device for the interior lights. This would be my next suspect, as it may have a separate set of contacts for the rear lights.
The bottom-left fuse in the fuse box ('Services') powers the interior lights, I believe. Of course you would expect the front lights not to work when you remove the fuse.
The electric mirror failure is most likely to be the directional switch, in my experience - probably requires de-oxidising and some Vaseline or similar.
-Alex