re: killing Will meaning they couldn't kill off Kalinda, very likely. Though honestly I think another reason was that Kalinda had been THE break-out character of the show in season 1 (Archie Panjabi was the first member of the cast to win an Emmy, which allegedly caused the problems with Julianna Marguiles, who didn't get her own Emmy until a year later) and despite a reduced role remained incredibly popular throughout the show. Will was mostly well liked, but he wasn't beloved in the same way. Killing the audience favourite is a serious gamble, especially if the audience favourite is female and one of your show's self declared goals is to offer a female centric narrative.

re: Peter running against Hillary Clinton, sigh. That sounds like a stupid storytelling choice for all the reasons you listed. Again: am glad I quit.