There's far too many holes in the whole concept to really be able to figure it out. Singer only loosely based his movie on the original 2 Superman movies. If he were to follow the original Superman II completely, there shouldn't even be a fortress of solitude as Superman went to it at the end and destroyed it.
There are alot of theories regarding Jason and the kryptonite. Personally, I thought that perhaps the kryptonite triggered his kryptonian genes and gave him the strength to throw the piano at the thug. Since he's half human, the kryptonite didn't bother him the way it bothers his father. I don't know if you noticed, but Jason no longer required the use of the inhaler after he threw the piano.
well, i've been out of college (or at least undergrad since 2002)
and in 2 weeks, i'll be done with graduate school completely and begin working a real job
hence the name change...lest people think i'm a professional student