>> “does the focus point indicator move as the subject moves or do I simply keep the highlighted focus point on the subject?”
The focus indicator should stay in one place and you should try to keep that point on your subject as much as possible.
I think 3d tracking works best when you subject is fairly large in the frame and moving relatively slow. It also uses the surrounding colors to help keep track of your subject. I would think this could cause problems in team sports where uniform colors could cause focus to shift to another player.
I would probably stick with either 9 or 21 point dynamic area AF for soccer or football.