Must he go to the Golah? Was he not already there?
Radak: He was in one place. Some of Bnei Golah to whom he was sent were elsewhere, also on the Kevar river. Ha'Golah can refer to Bnei ha'Golah, or the gathering of the Golah.
Malbim: This teaches that he was not sent to Bnei Yehudah in Eretz Yisrael, for there Yirmeyah was special for Nevu'ah. Yechezkel was sent only to Bnei ha'Golah.
Why does it add "El Bnei Amecha"?
Malbim: Do not go to prophesize to the nations, only to your nation. Also his Nevu'os for the nations, he was not commanded to prophesize to them like Yirmeyah was. Rather, Yechezkel will inform Bnei Yisrael.
What is the meaning of "Im Yishme'u v'Im Yechdalu"?
Rashi: Whether they will hear or refrain, say [the Nevu'ah] in front of them.
Why does it say "v'Dibarta Aleihem v'Amarta Aleihem"?
Radak: The matter is repeated in different words to strengthen it. Tell them time after time - perhaps they will listen!
Radak citing Targum Yonasan: Prophesize to them and say to them.
Malbim: "V'Dibarta Aleihem" at length; "v'Amarta Aleihem" that you do not speak on your own - Hashem commanded you!
