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Yep, "вы" and имя + отчество. Sometimes профессор, maybe (not very natural, imo).

Well, in this case, when addressing directly to him, usually it's just "доктор" (no name attached).
If you know him well (he's your attending doctor) you say Сергей Владимирович.
And if he's your...

Well, in theory, господин\госпожа is the same as mister\ma'am, Herr\Frau, monsieur\madame etc., but it's not used in everyday speech. Sad thing, Russia currently doesn't have any common honorific...