It means "what was your location during some time period in the past?". It is quite often used to refer to the last few hours/days/weeks, e.g. when you haven't seen someone for a while. But it can also be used for other lengths of time in the last, like "ow you travelled during the holidays? where have you been?".

It means "where were you?"

I think it's ok. For example you can ask it your friend who comes late