You can hit every kind of shot with every kind of forehand grip (ok, fh slice is hard to do with western grip
). If you keep playing with an eastern grip for a couple of weeks, your wrist will automatically get stronger and you'll be able to hit more from low to high and you'll also be able to pronate with more power without hurting your arm. Pronation basically is the rotation of your right arm counter-clockwise. When your arm just hangs down lose, pronation is turning the palm of your hand from the front to the back of your body.