Not the engine, but the emissions system. Overfilling can force liquid gasoline through the vapor line to the charcoal canister, where it destroys the charcoal. Repair is typically around $300 for a new canister assembly and blowing the liquid out of the line.

How would it damage your engine? The gas goes from the tank to the engine along a small bore pipe. The pipe doesn't know how full the tank is.

no it can not. If you overfill, some gas may leak out. There is a special valve to protect the tank.

Only if you spill the fuel on the ground and catch the car on fire.