engine block damage

Yes

Sure can. It can also cause head gaskets to leak, or heads to crack.

It may. You increase the likelyhood by adding cold water to an overheated engine. Hey, if yours overheated, refill it and see if it leaks. Watch the level for awhile, because it's possible of coolant to get into the crankcase without a visible. If the oil turns into a grey mass, kind of like thin putty, you've got a problem.

What kind of car are we talking about. Some are much more durable than others. How hot did it get, was it totally out of water?