The importance of Shalom

The Sifri records an argument over the last words of Birkas Kohanim, "and Hashem shall grant you peace." One Tanna says it means Shalom Bayis, peace in the home. Another says it means peace for the whole nation. Why would a blessing be read at two such different ends of the spectrum? And why does Parshas Naso, in the middle of counting tribes, suddenly stop for the very private matter of Sotah? The Mikdash Mordechai ties both questions to a phrase the Torah keeps repeating. Last comes a funeral where every kind of Jew showed up, and one quiet moment at a grave.