It is not possible to use a plastic explosive like C-4 to build an atom bomb. Explosive lenses to achieve a well-defined implosion can only be made out of rigid explosives.
Doctor McKay says he built a bomb for a school project. As a result of that, he was interrogated by the CIA. He is a Canadian national so it's more likely that he would have been interviewed by Canadian Security Intelligence Service (CSIS).
However, the CIA's remit is global intelligence gathering, so they might well have been concerned about this, especially since it was supposedly a (non-working) atomic bomb that he built.
At 25 minutes, the computer monitor used by the Genii in their laboratory is a Philco Predicata television set. The word "Philco" could be seen on the front of the base of the set, even though there are no English words or lettering on other Genii equipment.