I agree that Boba will not have a hand in Mace's demise because if his big bad daddy couldn't kill Mace, what chance will 13-15 year old Boba have?
There was some speculation about Dooku returning to the Light Side and him and Obi-Wan tag team Sidious and Anakin but I can't see that for reasons that are too numerous to post here.
Dooku will definitely die by Anakin I believe. I know that Obi-Wan is the one who forces Anakin to spend the remainder of his days in a walking iron lung. As far as the Jedi Council, some of them will probably be killed by Dooku and Sidious and the ones who survived will probably be killed by Anakin (except Yoda of course).
I know Padme died when Leia was young so I can only speculate that we will probably not see her die in Episode III. The reason being is that I am pretty sure Luke and Leia both are born in Episode III. So Leia would have to have a little age on her to remember Padme, even if it is "images really...feelings."