4) In fact, the FOPA did not ban machine guns; it simply requires people to pay a one-time Federal Excise Tax fee.
No. FOPA banned manufacture of machine guns for civilian ownership (aside from police and Class III dealers) if they were made after May 1986. The tax on machine guns is from the NFA passed back in 1934. Back then Congress didn't think they could ban guns so they put a $200 tax on what were generally $200 guns to make them less accessible. Granted, that made no sense because they were trying to keep them out of the hands of gangsters who had plenty of money thanks to prohibition which was another feel good political movement that didn't do any good.