First thing: Love both the anime and the manga, but the movies sucked. So let's really hope they do a good job.
And for the actors, just a quick though, but wouldn't ''Shea Le Boeuf'' (Feorgive for not writting his name right) be a good Kira ?
This is the guy who starred in the Transformers movie, and also played Indiana Jones son in the new movie.
He's a good actor, looks likhe a High School / College student, and since hollywood likes him, he could be a good choice.