Why does the Torah write "Vechaltzu es ha'Avanim" - in the plural?
Torah Temimah (citing Toras Kohanim): To teach us that if he shares a wall with a neighbor, whose side of the wall is not stricken, they must both remove the offending bricks and replace them. 1
And we learn from here the principle 'Oy le'Rasha, Oy li'Shecheino!' (Ibid).
What are the implications of "el Makom Tamei"?
Rashi: They must throw the bricks outside the town in a location where Taharos are not brought - because the bricks render Tamei the location where they are lying.