Tension is by far the biggest killer in the golf swing, gripping too tightly, standing in your set up too long, you need to keep your body in motion and relaxed to properly strike a golf ball
Hitting the ball with the bottom of the club face can result from several different swing faults
Flexibility as you get older is very important, it lets you wind up your body to hit the ball with more power, and swinging a pole can help you do this as well as fix your release point