I'd say that the pros cupping their wrists allow them to be power players. I don't exactly see Barnes or some others as power players. Fagan, TJ, Maximum Bob and maybe the Big Nasty are what I think of for power players.
Next, I'd say that they cup the ball on every shot. I think you can create the muscle memory to make such a thing as cupping the ball throughout the swing a habit. The problem I've noticed is a tendency to pull the ball into the swing at the start. but I guess what works for others may not work for me. Personally, I don't think that the pros are worried about the ball overhooking. They are pretty accurate for one, have a pretty good knowledge of the game and ball setups (I would imagine), and lastly, most of them are versatile in one way or another. That last one is the key to it all really. Being about to change so that ball doesn't go high, nor roll out.
Your other question has a lot variables. Are the balls drilled to react the same way? Are they met for different oil patterns? The bowler's ability to adjust and manipulate the ball's reaction? Do the balls have different surfaces?
It's easy to see the ball's hook potential for you. Bring both of your fingers (index and pinky) and throw either like you normally would or close to it. Or if you really want to see what it's "real" hook is like, use the same hand position and try to put the least amount of hook on it as possible. That should give you something close to it.
You are right in that cupping and uncupping the ball create more forward roll. However, in doing this technique not only do you get the added revs of the yo-yo effect, but you also get longer to apply the torque with your fingers to get the axis rotation right. This is why you are supposed to cup and c0ck your wrist. And the latter one isn't easy at all. Although I'm finding that cupping my wrist causes a slight c0cking of it. Not sure why. It is interesting though.
You can cup the ball depending on the wrist brace. That's why the word brace is there. They are meant to be training tools to build the muscle memory to first keep your wrist firm and from breaking than to get used to cupping the ball. Of course they aren't used like that, but that's a different subject altogether. And then there's the cybernetic arm brace that keeps your hand and wrist in a fix position for you.
Anyways, you can do both. And as sk8 says the more "advanced" release is with a cupped wrist. And well I say the more super "advanced" release is with a cupped and c0cked wrist.
Anywho, hope that helps and sorry for the long post. I had to catch up. LOL
The Demolition Man
Be like water making its way through cracks. Don't be assertive, but adjust to the object, and you shall find a way around or through it. If nothing within you stays rigid, outward things will disclose themselves.