1)
Why does it say "Teshalach Ketzireha Ad Yam"?
1.
Rashi: It sends its branches until the Yam ha'Gadol (Mediterranean Sea), the border of Eretz Yisrael. This is like "v'Asah Katzir" (Iyov 14:9).
2.
Radak: "Ketzireha" are the hard branches. They are until Yam Pelishtim, i.e. the entire length of Eretz Yisrael.
3.
Malbim: This is like it says above (72:8) "v'Yerd mi'Yam Ad Yam umi'Nahar Ad Afsei Aretz."
2)
What do we learn from "v'El Nahar Yonkoseha"?
1.
Rashi: This is the width of Eretz Yisrael, "umi'Midbar Ad ha'Nahar" (Shemos 23:31), i.e. the Pras river. Radak - it says also "Min ha'Nahar Nehar Pras Ad Yam ha'Acharon Yihyeh Gevulchem" (Devarim 11:24).
