Those expressions seem so strange I wouldn't even understand them. Is that archaic English? I've never learned anything about it... Here's some answers I would say:
1) She was very tall, but very sweet. Who? Who are you talking about?
2) Your friend sold me drugs! Oh, do you have any left? Who? Who did that? Who are you talking about?
If you wish to fit in with other people and accept them as approximate equals and have them accept you as an approximate equal, say: Who are you talking about? If you wish to set yourself above others and risk their laughter behind your back, say: About whom are you speaking? If you wish to set yourself very much above others and condescend to them as if to unciviliz