1)
Why does it say "mi'Nogah Negdo Ba'aru Gachalei Esh"?
1.
Rashi: Do not say that He dwells in darkness. Rather, there is light inside the partition, and from it coals burn; arrows were sent on Egypt. 1
2.
Radak: The light opposite Him is for His beloved; the burning coals are for His enemies. I.e. His fire illuminates for His beloved and burns His enemies.
3.
Malbim (Tehilim 18:13): The light came from [lightning due to the clouds that brought] the darkness.
1
I.e. hail, which descended on Egypt with fire (Shemos 9:24). Tehilim 18:13 mentions hail with the coals of fire. (PF)
