The number of players going into the box depends on your attack-mindedness at the moment, if I'm not mistaken. When you're setting up for the kick, hold L2 and press R1 to up the aggressiveness. Alternatively, holding L2 and pressing R2 will bring your defensiveness up, taking more people out of the box.
I think it depends on the attack-mindedness when the ball goes out of play, when I try to increase it when I am just about to take the kick nobody joins the attack.
When attack-mindedness is on red your defenders will come up, your keeper only comes up in stoppage time if you are behind by 1 goal.