Re: 11.5 inch upper question
If you want a SBR (less than 16") you need a registered lower. You can go the form 1 route, and get it engraved. Once you have the Stamp, build away. The other route is buy an already registered lower from your Class III dealer, and submit a form 4, then build away once you recieve your stamp.
Otherwise, if you have an upper that is shorter than 16" without a registered lower, your violating NFA.
Also check your particular state's law as well, a good class III dealer can help you with it.