To whom does "Mimech" refer to?
Rashi: It refers to Ninveh.
What was "Choshev Al Hashem Ra'ah"?
Rashi citing Sanhedrin 94b: Sancheriv thought to destroy the dwelling below and above. It says "v'Avo'ah Melon Kitzo" (Melachim II, 19:23), and it says "v'Avo Merom Kitzo" (Yeshayah 37:24). First I will destroy the dwelling below, and in the end the dwelling above.
Radak: Melech Ashur ascended to Eretz Yisrael and destroyed it, and thought to destroy Yerushalayim. "Al Hashem" means Al Am Hashem. Also, initially he thought that Hashem cannot save Yerushalayim from him.
Malbim: Melech Ashur denied Hashem's existence and Hashgachah.
What was the evil counsel?
Malbim: To cast off the yoke and do all abominations.
