1)
From when are the years counted?
1.
Mahari Kara, Metzudas David: From the reign of Tzidkiyah and the Galus of Yehoyachin; this was the year of the Churban.
2.
Radak: From the Galus of Tzidkiyah 1 .
1
Surely the text should say from his reign, like Radak explained everywhere else (24:1, 29:1, 32:1). If this is from his Galus, this was after the Nevu'ah in the 12th year of his reign (32:1). Radak should have explained why this is out of order! (PF)
2)
What is "ba'Rishon"?
1.
Radak: In Nisan, the first month.