Quote
Below that meter, is that some kind of a Service fuse?.
I think so, probably between meter and main panel. If you look closely there's only one switch, that would be damn small, even for Italian style. Modern breaker panels look pretty much the same like everywhere else in Europe and seem to use double-pole breakers.
When i was in Torino two years ago, the main breaker would trip when the electric water heater and the electric range were on at the same time. Somebody would go into the dark hallway, take down a painting hiding the meter box and reset the breaker.

Quote
In that most recent pic with all the line taps, does another set of wires run into what looks like a square trunking, to the right of the conduit dropper?.

No, I think that's a rail for a sliding door.

If the two wires (blue and grey) exiting the meter base are the feeders to the main panel I know why said breaker occasionally tripped! Sure they're no more than 4mm2, which means a max. of 25A service fuse, rather 20.