Why should everyone gather?
Radak: I created everything; and I lower this kingdom and raise another, e.g. I will lower Bavel and raise Koresh. When I gather all of you, does anyone among you know the future events that I will do?!
Malbim: To hear the question that I will ask.
What is the meaning of "Mi Vahem Higid"?
Radak: Who told [the future events that I will do]? Radak - even though the verse began in second person "Hikavtzu Kulchem", it switches to third person "Mi Vahem." Verses do so, e.g. "Shim'u Amim Kulam" (Melachim I, 22:28).
Malbim: Who in Shamayim or Eretz told the following matters?
What is the meaning of "Hashem Ahevo Ya'aseh Cheftzo b'Vavel u'Zero'o Kasdim"?
Rashi: Hashem loves the one who will do His desire in Bavel; his arm will be seen in the land of Kasdim. This refers to Koresh.
Radak: Several verses already said that Koresh will destroy Bavel; the verse relies on the reader to understand that it refers to him. Hashem's arm will be seen in Bavel, for Koresh [attributed his conquest to Hashem; he] did not aggrandize himself about his strength 1 , like Sancheriv and Nebuchadnetzar did. He said, "Kol Mamalachos ha'Aretz Nasan Li Hashem Elokei ha'Shamayim" (Ezra 1:2). It should say b'Kasdim; the prefix Beis is omitted. There are many verses like this, e.g. "Liznos Beis Aviha" (Devarim 22:21) means b'Veis Aviha.
Radak citing Targum Yonasan: Hashem, who loves Yisrael, will do His desire in Bavel...
Malbim: Koresh, whom Hashem loves, will do His desire in Bavel, to destroy it. His arm (power to do so) is the Kasdim themselves. Belshatzar's officers killed him, and informed Koresh, and helped him to destroy Bavel.
Presumably, this is why Hashem loves him. (PF)