What is the gist of Hashem's words?
Radak: Ashur and Egypt will be wiped out, for they did not know Me. You will know that Hashem does evil to whom He wants, and benefits who He wants, i.e. the residents of Yerushalayim. Melech Ashur, who destroyed Yisrael (the 10 tribes), [the rest of] Yehudah and Egypt, will come to destroy Yerushalayim. He will not be able to, for Hashem will not want.
What is "Yehgeh"?
Rashi: It is making one's voice audible, like "Hago Nehgeh" (59:11).
Radak: It is like roaring.
What is the meaning of "Asher Yikarei Alav Melo Ro'im"?
Rashi: When it calls with its great voice, many shepherds will gather to it 1 . Also "Kar'u Acharecha Malei" (Yirmeyah 12:6) and "Yachad Alai Yismala'un" (Iyov 16:10) refer to gathering.
Radak: Yonasan translated Yikarei be summonsing.
Radak: In order to save its prey from it.
What is the meaning of "Lo Ya'aneh"?
Rashi: It will not be humbled and make itself an Oni. The same applies to "Le'anos Mipanai" (Shemos 10:3).
Radak: The lion is not afraid of the voice of the shepherds; it will not abandon its prey due to them.
Malbim: Hashem's salvation of Yerushalayim was without any preparation below. Also the people just trusted in Hashem, like a lion is confident about [getting] its prey, and is not humbled due to the voices of all who gather against it. However, Hashem fought from above to save them (5).
Why does it say "Ken Yered"?
Rashi: So Hashem [will descend to fight on Har Tziyon] without fear of the multitudes of the nations.
What is the meaning of "Litzbo"?
Radak #1: To (against) the camp arranging its troops against Tziyon.
Radak #2: [Hashem will] arrange troops against the army of Machaneh Ashur.
Why does it say "Giv'asah" (feminine)?
Radak: Tziyon is feminine - "Tziyon Hi Doresh Ein Lah" (Yirmeyah 30:17).