What exactly is that flat spot during the release?
That was answered in a recent thread.
How do I keep the ball closer to the body without actually hitting my ankle?
Move your slide foot to the center of your body, aligned with the shoulder and chin.
I have read about the cupping and uncupping of the wrist and keeping your wrist in the postion you want the ball to roll. Which is the most effective way for a consistent release with a good amount of revs?
You can do that release without the cupping/uncupping until you feel comfortable with it, then add the cupping/uncupping for extra revs. In addition, you can flip the wrist over the top of the ball as a continuation of the uncupping motion for even more revs (make a fist).
How do you actually work the inside of the ball?
That's a different release style. If you swing hte ball with the hand on the inside of the ball, then you'll have to rotate the wrist in order to get some spin. The more rotation, the less control you will have, so just a very minimal rotation, done very quickly. Also, crankers work the inside. You don't want to imitate them (e.g. Tommy Jones) until you have the strength.
Also, during the release, I try to stop squeezing the ball. This has worked somewhat.
Don't ever squeeze the ball at any time, from start to finish.
My thumb feels as if it is being pulled by the ball and is putting pressure on the side of my thumb as I bowl. It feels as if it is about to slip. When I keep my nail to the back of the hole, it put pressure on the side of my thumb by the knuckle. What is wrong?
All my balls are 15 pounds, should I go down a pound on my next ball purchase?
I doubt it. 15 is the most popular weight for men. To get stronger, go down to Target and buy a couple of kettlebells and do wrist curls. Although, come to think of it, I was using 14 pounds at your age....
A final note - in bowling, the only muscles you use from the shoulder to the fingertips are the forearm muscles connected to the wrist. You don't use and upper arm muscles - deltoids, biceps, triceps. The swing should be a pendulum swing, with the hand falling at the same rate that the ball is falling. The wrist muscles come into play at the bottom of the swing as the weight of the ball transfers to your hand in each direction. On the forward downswing, however, you are beginning to uncup right at the bottom of the swing, so really the muscles are required on the backward downswing moreso than the forward one. Cupping is an extra, and is not really necessary. Just a firm wrist will get you enough revs to hook a brand new ball. If you have an old worn out ball, you will do what I did - try a lot of ways of rotating the wrist to get the ball to hook. You can watch sk8's and cgeorg's videos on YouTube for some good examples of form and release. Their youtube names are sk8shorty01
. Another two good youtube users are BowltechBowlingTips
. They have some great instructional videos. Just type in the user name in the search bar at youtube to find the videos.