Pesachim 6: More interplay between Jews and non-Jews, and ownership of chametz (by a non-Jew) in a Jew's space. Note the historical acknowledgement that Jews could not always, or usually, rent to a non-Jew (Syria being the counter example). Also, the significance of the requirements to check for chametz kicking in (or not) for those who are not home from 30 days before Pesach. Also: Thr concept of Ein Mukdam u-Meuchar ba-Torah -- no chronological order in the Torah -- and that of "kelal u-prat u-kelal" are employed.