I agree manofsteel.
Regarding Jason, naturally, the father-son dynamic is most certainly there. As someone earlier said (in a negative way), Singer made Superman lonely. But he is the last of his kind, so why the devil wouldn't he be lonely.
Now though, he knows that he isn't alone. His legacy is important, but he is, at heart, human. He desires companionship. We are social creatures, and Jason gives Supes that social connection. Jason is part Kryptonian, part human. Thus, he becomes a sort of conduit, a way for Supes to feel more human than he ever has before.
As far as Jason's arc goes, I'd say his powers would be starting to manifest themselves during the movie, and Supes is concerned, trying to protect him from Luthor and from whoever the other villain is (my bet is on Brainiac).
And I have faith that Singer will handle him very well. Singer knows how to work with kids to make them work believably (instead of the abominable Legend of Zorro).