Well, I can help you with the Will part. The writers say that if Will came back and his true love was waiting after the first ten years, he'd be free of the curse forever.

That's why Davy Jones was so ticked at Calypso. He had the chance to be free, but she wasn't there, so he cut out his heart.

I'll give you links and stuff if you want more information, but I have to leeeave now. =p