1)
Why does it say "va'Yimloch Melech Tzidkiyah"?
1.
Radak: Tzidkiyah is called a king - but the previous king, Yechanyah, who ruled only three months, is not called a king.
2.
Malbim (28:1): He was already king before he ruled by himself - "Asher Himlich Nebuchadnetzar" (in the days of Yehoyakim).
2)
Why does it teach here that Tzidkiyah became king?
1.
Rashi: It comes to teach how the predicted punishments were fulfilled. When the time came to fulfill them, a new king ruled over Yehudah, in place of Kanyahu ben Yehoyakim.
