In the British system the female equivalent of address to Sir for a British knighthood is Dame . This can be the title of a woman who has been made a Dame Commander or Dame Grand Cross of the Order...
yes
Some knights were called sirs as they were knighted by a king/Queen for different reasons.
NO because they were around at different times
In the movie "Knight & Day" Tom Cruise's Characters' real, non-undercover name is Matthew Knight.