1)
What is the connection between this verse and the previous Nevu'ah about the Seforim (verses 25-28) and the Nevu'ah after this?
1.
Malbim: He had the previous Nevu'ah when (after) Tzefanyah read the Sefer to him. Since Shemayah sent letters that sprouted brazenness, to the point that he read the Seforim in the ears of Yirmeyah, the following Nevu'ah was said.