There are extension boxes that add depth to the existing box.
Technically no, as long as you can avoid touching the wires on the outlet or switch...
Each pack has 25 strips of spacers which easily break apart with your fingers. They stick together like legos and you simply use as many as are needed to space the switch/outlet out of the box, so that it is flush with the wall, so the faceplate fits cleanly. It’s a great sensible product. So far I have done 11 switches/outlets and I am not through the first bag yet!
Yes, they can.
Yes, easy way to shim receptacle to a receptacle box a little too deep inside wall because add paneling or tile . Receptacle box should have been out to account for additional wall panel, tile thickness.
You can stack as many together as you need for the desired thickness.
I would assume so. Pretty common. I am not an electrician, full disclosure!