1)
What is "va'Yar'em"?
1.
Radak: He made thunder in Shamayim on the enemies, and put His voice on them. He put fear in their hearts, and they feared Him like one trembles and is befuddled due to thunder.
2)
Why does it say "Barad v'Gachalei Esh" Verse 14 already said so!
1.
Ibn Ezra: It is to mention it together with the thunder.
2.
Radak: Together with the sounds were decrees to eradicate [the enemies], which are like hail and burning coals.
