Can Queen Elizabeth change the succession to the Throne if she wanted to?
Could she skip Prince Charles (and Camilla) and make William king?

This may help;

Succession (http://www.royal.gov.uk/ThecurrentRoyalFamily/Successionandprecedence/Succession/Overview.aspx)

Damn, my great-great-great-great grandfather was the Duke of Bedford, and not in the list. And I thought if a dozen or so people were to vanish I could be King of England.

I think Charles will be a good king, assuming he outlives his mother.

From what I have read, no she cannot. It would require a change in British constitutional law for her to pass the throne to him. She can however, deny him the throne and live forever. (this is a movie quote, I just couldn't see when I'd ever have an opportunity to use it again)