How, exactly, could Cain have "known" that his past was going to come up, when, as I have just established, there is no reason to believe that any of these accusations have any basis in reality?  (And why would he have reason to believe that confidential documents from a decade and a half ago would be the trigger for a high-tech lynching?)

Do I think that Cain could have handled it differently?  Sure, but I'm not the guy actually in the arena.  (Armchair quarterbacking is easy; try actually being a quarterback sometime.)