Do ghosts have to hover?

I’m trying to figure out the rules around flying creatures – particularly those that only have fly speeds and if that means they effectively have 2 actions a round due to a required hover.

  • Looking at a Ghost Commoner does it need to spend an action every turn to hover to avoid falling?
  • As an incorporeal creature is falling even a concern?
  • If it does have to hover to avoid falling does that also provoke Attack of Opportunities since Hover is tagged as a move?