Lyman,
I'm somewhat reluctant to reply to your questions, because the 'level bust' incidents have been discussed at length in various threads and have no relation to AF 447.
Since the High AoA protection is not available in ALT 2b. it can only occur if the airplane remains in Normal law.
Yes, it is possible for AoA to exceed Alpha Prot in Auto. IIRC that occurred in the Turkish level bust due to turbulence. The AP disconnects when that occurs.
Your last question - if the PF failed to notice the indications on the PFD and ECAM and did not hear the PNF's announcement, it is possible he was not aware of the law change.