Section 1-does this interere with regional gun laws? If so, would regions be able to pass a law in the future banning gun ownership?
It does not interfere with regional law; in fact, it explictly refers only to "federal law." Regions are free to legislate as they please, within the bounds of the Constitution and their own constitutions.
The Bill of Rights would be violated if this were imposed by the government. There is a right to free speech.
If the reasonably should know is striken, there is no problem, but while it remains there, if I sell you a gun, how am I "reasonably" suposed to know if you are going to use it unlawfully or not?
That's a standard legal phrase. "Beyond reasonable doubt," "reasonable person," "reasonably should know" are all accepted terms.
One example would be giving a gun to an infant, whom you should reasonably know would not use the gun in a proper manner.