12/2 15 or 20 amp
Are you sure about this code requirement? That is one I never heard for NJ.
If you are using #12, use 20 amp breakers. Period. There is NO reason to use 15's.
The only exception would be if the circuit is VERY long, like over 125' or so, and will be heavily loaded. Like for use with an iron or vacuum.
As long as there is at least one duplex receptacle on the circuit you can use 15 amp rated receptacles. There is no reason to use 20 amp rated receptacles unless you have a specific appliance that requires one, which is extremely rare.
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.