1)
What is the reason for girding sackcloth, eulogizing and wailing?
1.
Rashi: It is like the verse concludes - because Hashem's anger did not depart from us. Malbim - it is not due to the previous verse, that your land and cities will be desolate.
2)
What is the Chidush that Hashem's anger did not depart?
1.
Rashi: Yoshiyah repented "b'Chol Levavo." However, "Lo Shav Hashem me'Charon Apo