Hope this is helpful!!

Of course it totally depends on the context. You cannot answer this question unless you know how often these people meet, how close they are, and what the situation is like. This answer can be when the two people are reasonable close to each other but haven't seen each other for a while. That's what I think.

お元気ですかis the text book translation of How are you? but hardly used in normal conversation. If you are on good enough terms with a person to be discussing their health ( as opposed to making some more formal greeting) then you would not use such a stilted phrase. Even,元気？( with rising intonation ) or 　最近どう？ would be better.