Vs. 1-5 ~ The Lord is summoning His forces from the ends of the earth in preparation for a "holy war."
Vs. 6-7 ~ In v7, "every man's heart shall melt" means that everyone will be afraid, for when Christ comes He will destroy the wicked. Remember that these verses can be takes literally as well as figuratively.
Vs. 8 ~ "Isaiah compares the trembling fear and shaking terror of the men to the anguish of a woman in labor. 'But whereas a woman in labour cries, men will only stare at each other aghast in horror and begin to sweat from fear.' [Kaiser, "Isaiah 13- 39," p16] (Ludlow, p184)
Vs. 9 ~ The reason the Lord is doing all of this is to purge the earth of its wickedness.
Babylon was easily conquered when the Medes came from Persia. In v10-16, Isaiah describes the physical consequences that will come upon Babylon and her people at this time.
Vs. 17 ~ Sometimes attackers can be bought off with money... but that is not the case here.
Vs.18-19 ~ Again, Isaiah is speaking literally (destruction of Babylon by the Persians) as well as in a spiritual sense (destruction of the worlds wickedness, which is Babylon). Who's REALLY behind all of Babylon's wickedness and who has REALLY ruled with blood and horror on this earth? It is Satan who is behind it all. He is the king of that world. The Old Testament says he rules from the rivers to the ends of the earth. ("Rivers" also mean big city centers, and also borders of countries. Lucifer is the king of wickedness and rules over all the tyranny, horror, bloodshed, greed, apostasy, and selfishness found on this earth.
What did you learn?