by artax1
You got the answers right.1. A building can indeed be activated as many times as you wish as long as it is unoccupied, that is only after gathering your citizens on your Plaza card, thus clearing the building.
2. You never place a citizen on a character card to activate it, as you do with ordinary buildings. Character cards simply interact with the cards situated in the same row or column in the way described by the symbols (see player aid for the symbol explanation).
3. Prestige buildings must not be activated. Activation is only possible for Level I and Level II buildings. The only function of prestige buildings is to earn their owner (and the other players to a lesser degree) Prestige Points at the end of the game.