1)
Why does it say "l'Cherpah l'Shamah
1.
Malbim: At the end of days it will be destroyed forever, like Yeshayah prophesized (Perek 34).
2)
What is "Batzrah"?
1.
Rashi: It is a city of Mo'av. However, due to the matter "Yovav ben Zerach mi'Batzrah" 1 (Bereishis 36:33), it will be punished with Edom.
2.
Radak, Malbim: It is the capitol of Edom.
1
I.e. they supplied a king for Edom (Rashi Yeshayah 34:6 citing Pesikta).
3)
What are its (Batzrah's) cities?
1.
Malbim: It refers to the cities of the country.
