Coming up out of posture during the downswing is a common fault created by a lack of strength in the glutes (buttocks), try stretching and strengthening them by lying on the ground with your knees bent and lifting your hips and buttocks off the ground for ten seconds
Create a pre shot routine in three phases, one where you visualize, one where you align and one where you pick a key to initiate the swing
Heel shots are caused because you either move the center of your plane out towards the ball during your swing or you start too close to the ball at address