As to the name, Bill Smith, - his middle name is Clark. Leave it. After all, if he was raised by someone else, it makes sense that his name would be different. That doesn't change who he is.
I don't think there was ever an IQ or anything about him being really smart ever mentioned on the show - other than him being able to speak lots of languages and order food in even more languages.
The comics have (you know how often they change, though) have said that he was a 4.0 student and very smart.
That's one thing I don't like about Smallville - Clark should be excelling in school. All Clark's should excel in school. Anyone who has a photographic memory and can read that fast should do well in school. Maybe the Smallville Clark doesn't know that yet.... (And off topic, doesn't Tom Welling just have the prettiest blue eyes you've ever seen?)
