GF represents Guard/Forward. Meaning that the player has the physical and athletic ability to play at least one of the guard positions or one of the forward positions while on the court. You usually find this to be the case when a player is traditionally larger than a guard but possesses the shooting touch and ball handling skills required of a guard. A coach can sometimes use this player to create match up problems with the other team.
Example: Francisco Garcia on the Sacramento Kings is 6'6 and can play either guard or forward. Paul Pierce. 6'6, can play either guard or forward.
There is no connection between a basketball player's number and the position he or she plays.
center (a player position)
There is no position with w, but w could mean wing which is a guard
Traditionally the Center position is played by the tallest player.
You can either drive it, pass it, or shoot it
forward centre it is actually cf not fc