It means something in New York State, and other states where there are "assault weapons" bans of their own.
No it doesn't. The Firearms Freedom Acts are laws passed by the state legislature. My guess is you are extremely unlikely to find a Firearms Freedom Act bill and an Assault Weapons Ban coexisting - and even if you did, the Firearms Freedom Act only asserts freedom from FEDERAL regulation, so the ban would still be valid.
All of these bills are currently being challenged in litigation. The Second Amendment Foundation is supporting that fight.