Resignations over scandals often raise more questions than they answer, and that’s true of Gen. David Petraeus’s abrupt exit from the Central Intelligence Agency. Some have already been put to rest: Paula Broadwell, the co-author of “All In: The Education of David Petraeus,” has been identified as the woman at the center of the FBI email probe that ultimately toppled him. But many questions remain. Here are POLITICO’s six most important: 1. Why resign now? The Obama administration’s first sex scandal exploded just three days after the president was reelected at the end of a hard-fought campaign and just days...