1)
The Nevi'im were mentioned above (25). Why are they mentioned again?
1.
Radak: They caused all the evil.
2.
Malbim: Not only did they not rebuke the Kohanim and officers ? they helped them [to sin] via false Nevu'ah in the name of Hashem.
2)
What did they plaster?
1.
Radak citing Targum Yonasan: The false Nevi'im in [the city] were like those who build a wall and smear it with inferior plaster 1 without straw. Rashi ? the plaster (mud) was not processed enough. It melts by itself when rain comes on it. Anything not fixed is called Tafel; here, it lacks straw.