Why does it say "Hayah Hayah [Devar Hashem?]"?
Rashi: Hashem already spoke to him, for the Shechinah dwells on a Navi in Chutz la'Aretz only if it already dwelled on him in Eretz Yisrael 1 . The Sefer begins "Ben Adam Amod Al Raglecha" (2:1); the Navi is not in order. Some say that it begins "Ben Adam Chud Chidah" (17:2). I say that it was told to him before they were exiled. It was proper to be said to him in Eretz Yisrael. It does not mention Golah. It was his first mission [to Bnei Yisrael]. Also Yonason translates [that Hashem previously spoke with Yechezkel in Eretz Yisrael].
Mo'ed Katan 25a, Mechilta.
What was the purpose of this Nevu'ah?
Malbim: It was to console the exiles. They should know that the Shechinah is with them also when they are in the land of their enemies.
Above and below, the Navi is in first person "va'Ani b'Soch ha'Golah? va'Er'eh", "va'Ere v'Hinei Ru'ach" (1, 4). Why are verses 2-3 in third person "Hayah Devar Hashem El Yechezkel? va'Tehi Alav" (3)?
Rashi (1): Verses 2-3 interrupt the Navi's words, to teach his name and the year.
Radak: Sometimes verses switch from first person to third person, e.g. "Neshei Lemech" (Bereishis 4:23), "v'El Moshe Amar Aleh El Hashem" (Shemos 24:1), "v'Es Yiftach v'Es Shmuel" (Shmuel I, 12:11).
Why does it mention also his father's name?
Megilah 15a: The verse names a Navi's father only if also his father was a Navi.
Radak citing Targum Yerushalmi: Yechezkel was Yirmeyah's son. Yirmeyah is called Buzi, for they were Mevazeh (disgraced) him.
What is "Nehar Kevar"?
Rashi (1): This is the name of the river. Radak (1, 3) - he was on the bank. When He speaks to a Navi in Chutz la'Aretz, it is only in a Tahor place 1 , on water 2 , like here, and "va'Ani Hayisi Al Uval Ulai", "va'Ani Hayisi Al Yad ha'Nahar" (Daniel 8:2, 10:4). "Kum Tzei El ha'Bik'ah" (below, 3:22) teaches that a valley is Kosher [for Nevu'ah in Chutz la'Aretz].
Radak (1): Yonason translates this to be the Pras river. Magidim say that Kevar is Pras 3 . Chachamim argued about this (Bereishis Rabah 16:3). R. Yudan said so; its Peros are big, and do not pass through a Kevarah (sifter). Rav Huna says, Kevar is not the Pras.
What is the significance that "Yad Hashem" was on him?
Rashi: Every "Yad" in this Sefer and in Nevu'ah is strength. Nevu'ah takes effect on him Bal Korcho (against his will), like one who goes crazy.