From when are the six years counted?
Rashi: It is from the exile of Yechanyah.
When is "ba'Shishi"?
Radak: It is in the sixth month, Elul. Malbim, Seder Olam - it was a leap year, for he began prophesizing in the fifth year, on the fifth of Tamuz. He was silent for seven days, and then Hashem told him to lie on his side for 430 days. In order to finish before the fifth of the next Elul, we must say that it was a leap year. Radak - Seder Olam holds that he truly slept on his side. I explained that it was in a prophetic vision (so we need not say that it was a leap year).
Who are "Ziknei Yehudah"?
Radak: They are those who were exiled with Yechanyah (ha'Charash veha'Masger).
How was "Yad Hashem" on him?
Radak: When a spirit of Nevu'ah comes strongly, it is called Yad Hashem. This is mentioned regarding these three visions in which he saw Ma'ase Merkavah. They correspond to the three exiles - of Yehoyakim, Yehoyachin and Tzidkiyah. This last one corresponds to Galus Tzidkiyah; he saw the honor travel from the Beis ha'Mikdash, and Churban of the city and ha'Bayis. Therefore, He brought Yechezkel to Yerushalayim to see the idolatry due to which the honor departed, which led to the Churban. So the Torah says - "v'Histarti Panai Mehem... v'Amar ba'Yom ha'Hu Al Ki Ein Elokai b'Kirbi Metza'uni ha'Ra'os he'Eleh" (Devarim 31:17).
