Mixing and matching couplers and trucks on narrow gauge railroads

I am going to really show my ignorance of engineering principles here with these questions. I would say it is pretty common knowledge that the various narrow gauges used different sizes of automatic couplers. The Rio Grande seems to have used the largest coupler in the narrow gauge world so to speak.

Can different size automatic couplers be used together in service safely?

Was this practice common at all where narrow gauges interchanged with each other, i.e. the C&S and the Rio Grande?

Can different size trucks wind up under a piece of rolling stock and not have it be a disaster? A 3'7" truck and a 4'0" truck for example.

Can different styles of trucks be operated on the same car if they are the same wheelbase?

Thanks!