Why does the Torah add the 'Hei' in "ha'Aretz"?
Ramban #1 (citing Ibn Ezra and Rashi in Bereishis 31:13 1 ): It is similar to the Pasuk in Divrei ha'Yamim 2, 15:8 - "veha'Nevu'ah Oded ha'Navi" - and is as if it had written 'el ha'Aretz, Eretz Kena'an. 2
Ramban #2: It means 'the land (that is called) Kena'an (after its inhabitants). 3
Why is it necessary to define the borders of Eretz Yisrael?
Rashi: Because many Mitzvos only apply inside Eretz Yisrael, and not in Chutz la'Aretz. 1
Meshech Chachmah: Bnei Gad and Bnei Reuven may not return to Ever ha'Yarden until Yisrael conquer and divide the land within these borders.
Meshech Chachmah: Even though most Mitzvos apply also in Ever ha'Yarden (what they captured from Sichon and Og), some apply only in Eretz Yisrael proper, e.g. Bikurim.
Why does the Torah use the word "Tipol ... "?
Rashi #1 and Seforno: Because that is the expression that goes with the lots 1 by which the land was divided.
Rashi #2 (citing a Midrash Agadah): It hints at the fact that Hashem cast down the angels of the seven nations of Cana'an and bound them in front of Moshe. 2
What are the implications of the word "Zos"?
Seforno: To preclude the land that they captured in Chutz la'Aretz , which did not require lots. 1