1)
What is the meaning of "Ki Avdu Vam"?
1.
Rashi: [Others] will force Bnei Bavel to work for them [Radak - like they forced all nations to work for them. The verse writes past tense in place of future.]
2)
Who are "Goyim Rabim"?
1.
Rashi: Madai u'Faras. Radak - the great kings are of Madai u'Faras.
2.
Malbim: It is all the nations that until now, Bavel forced them to work for Bavel.
3)
How will Hashem pay them like their deeds?
1.
Malbim: They will receive the evil that they did to others.