Who is "Avdo"?
Rashi: It is Moshe.
Radak: It is Yeshayah.
Malbim: It is Tzadikim. Due to their decree 1 or Tefilah, I will annul the decree of the stars, Kosemim and scientists. All of them said that Bavel will succeed and Yerushalayim will be low.
Malbim: We find that Eliyahu decreed "Im Yihyeh ha'Shanim ha'Eleh Tal u'Matar Ki Im l'Fi Davari" (Melachim I, 17:1), and Hashem fulfilled.
What is "Atzas Mal'achav"?
Rashi: One angel told Yakov "Yisrael Yihyeh Shemecha" (Bereishis 32:29), and You fulfilled his words. Also here, I will fulfill the counsel of My Navi, who says that Yerushalayim will be settled.
Radak: They are Nevi'im other than Yeshayah who prophesized about building Bayis Sheni.
Malbim: A Navi requests a sign so people will believe his Nevu'ah
Why does it say "li'Yrushalayim"?
Radak: This is Ba'avur (for the sake of) Yerushalayim; the same applies to "l'Ari".
What is the meaning of "Tushav"?
Radak: Its residents will return to it. The root is Yashav. The verse did not mention who will do so.
What are "Charvoseha"?
Ibn Ezra #1: The ruins of every city.
Ibn Ezra #2, Radak: The suffix Hei shows that this refers to [the ruins of] Yerushalayim.
Malbim: The destroyed parts of Yerushalayim - the Mikdash and the Azaros.
Why does it say "Akomem"?
Malbim: I will raise them Myself, in My honor.