Shinzon wanting to destroy Earth didn't make much sense to me either.
Yeah, that bothered me as well.
A scarred version of Patrick Stewart would have been it.
Shinzon was supposed to replace him. So let him be the same age.
Exactly. Hardy is very good but Stewart _is_ Picard, so it would have made the "reveal" a lot more poignant. As it stands they have to tell you it's a clone, but the crew act all shocked.