1)
What is the significance of the two sets of Mitzvos, one here, and one in 6:1?
1.
Ramban: The former refers to the Aseres ha'Dibros, which they heard directly from Hashem; the latter, to the rest of the Torah, which, following their request - with which Hashem agreed, they heard from Moshe Rabeinu. 1
2.
Seforno (on 6:1): The former refers to the Mitzvos that applied to them until now; the latter, to the Mitzvos that were connected to Eretz Yisrael 2 , which would take effect only once they entered Eretz Yisrael.
2)
What are the connotations of "ve'Lo Sasuru Yamin u'Semol!"?
1.
Seforno: It means that they should not add to the Mitzvos or subtract from them.
