Regarding the flight control law questions:
No entirely true. In normal law the flight contol computers provide various protections which keep the aircraft within operating and structural limitation. The first level of degradation is alternate law in which some of those protections are lost, but the aircraft still flies normally. The next level of degradation is direct law, at this point, the aircraft does not have any protections but still flies like any normal aircraft with full control authority. The last level of degradation is manual back-up where the pilot has only rudder and manual pitch trim to control the aircraft while computers are reset. Manual reversion is not designed to be used to control the aircraft in other than straight and level flight as a temporary siutation. I have landed the 332 in the sim in manual reversion and it can be done, but the chances of being in that situation are exceedingly slim.
Regarding the PRIM and SEC question, the loss of PRIM 1 and SEC 1 would probably leave the aircraft in alternate law which is not an emergency situation in itself but would be another distraction if more failures were occuring. With any 1 of the 3 prims, and 1 of the 2 secs the aircraft is in normal law. The degredation logic is somewhat complex, but with any 1 of either type of the flight computers you could at least have direct law.
The flight computers are all independently designed and built by different companies to ensure that a design or manufacturing flaws could not affect all of the computers.