What is "Mir'eh Tov"?
Malbim: It is a place to graze during the day.
What is "Harei Merom Yisrael"?
Radak: It is Yerushalayim, which is higher than the rest of Eretz Yisrael and all Yisrael will have a dwelling in Yerushalayim in the future, like it says at the end of this Sefer.
What do we learn from "Sham Tirbatznah b'Naveh Tov"?
Malbim: Flocks need a place to lie down at night. It is called Neve Tzon. The place will be in mountains, safe from Chayos and bandits.
Why does it add "u'Mir'eh Shamen Tir'enah"?
Malbim: Normally, mountains are not fat (fertile), and it is not a good place, for it is hard to ascend. The verse teaches that it will be fat and good ? they will be able to graze there, and will not need to descend to pasture.