1)
Here it says that that he passed his son in the fire. In Divrei ha'Yamim II, 28:3 it says that he burned his sons in fire!
1.
Malbim, from Sanhedrin 63b: Chizkiyah's mother had anointed him with blood of the Salmandra (a certain Chayah), so he did not catch fire. Achaz' other son burned in the fire.
