1)
Why did he put Mizbechos to the Heavenly legion in the Chatzeros?
1.
Malbim (Melachim II, 21:5): The Mizbe'ach to Hashem was inside the Heichal. He made it seem that Hashem is like a king conducting matters inside, and the Heavenly legion runs matters outside.
2)
Why did verse 4 say "Banah", and here it says "va'Yiven"?
1.
Malbim (Melachim II, 21:5): When the Vov switches future to past, it shows that the action was done repeatedly 1 ; it is close to present tense. Building Mizbechos to Hashem inside did not complete his purpose. It was finished only when he built Mizbechos to the Heavenly legion.
1
This is unlike Rashi! Refer to Bereishis 4:1:1:1. (PF)
