Only while incarcerated or as a condition for release as part of punishment from a trial. However, the CGA of 1968 is a FEDERAL law that the Constitution expressly says the Feds had no power to pass. Same for the NFA of '34 and the FOPA of '86. The 1989 Import Ban is debatable.
No mere State level restriction on RKBA is accepatable as a priori restraint on law aibiding citizens.
Agree, as part of a punishment, yes.
The federal government would IMHO have the authority to extend such punishments to people if they travel to other states (Fair Faith and Credit clause) but only in cases where the sentencing state imposed them. For the federal government to apply its own rules to when such a ban applies has no constitutional basis.
As for the 1989 import ban, it may be constitutional to restrict the actual importation of certain items, but I see no legitimate basis for restricting what people can do with the items once they've been legally imported.