The fifth season of “Mad Men” premiers Sunday on AMC, marking the return, after a 17-month hiatus, of Don Draper and the gang at the advertising firm Sterling Cooper Draper Pryce. For the latest on “Mad Men,” we suggest you pay a visit to our colleague Jen Chaney’s blog, Celebritology, where you can get a “preparatory guide,” or read Washington Post critic Hank Stuever’s review of the upcoming season (he promises no spoilers).