1)
What is "mi'Kol Nispesah Vavel Nir'ashah ha'Aretz"?
1.
Radak, Targum Yonasan: From the sound of the capture of Bavel, the land shook (like an earthquake).
2)
Why does it say "u'Ze'akah ba'Goyim Nishma"?
1.
Radak: It is as if it says v'Kol Ze'akah. "Mi'Kol" applies also to Ze'akah.