Sitting in a wifi cafe doing a little Bible study:
This chapter is filled with familiar imagery -- we have the famous 144,000, remember from previous chapters that this is a symbolic number signifying completion (12, 12,000's) they are unique from all other humans and are specially selected. Notice in (2) that there is a sound like harpists playing harps (we knew playing harps would play into the heavenly scene eventually). (8) Babylon is Fallen -- more about this in later chapters - remember that Babylon was the great evil empire of the Old Testament. Babylon sacked and destroyed Jerusalem and carried the nation of Israel into exile. John uses "Babylon" to mean every and all evil empires -- in John's time the evil empire was Rome. Babylon has had many faces, names and configurations over the years. Any empire that forces its will on others or forces people to leave the worship of God is "Babylon" in the biblical sense.
The "Grapes of Wrath" takes its title from this passage. And, most of us when we read this, hear the strains of the "Battle Hymn of the Republic" remember the line "he has trampled on the vineyards where the grapes of wrath are stored"? That is from the older translation language of this chapter.
13 and 14 are part of the funeral liturgy -- blessed are the dead who die in the Lord . . . they will rest from their labor, for their deeds (works) do follow them."
The earth is being harvested - this image has more to do with the completion. Remember that the Biblical view is that Earth was created by God for a purpose and that purpose is being worked out. When the completion of something has arrived -- the benefit, the harvest is received. Here in 14 the harvest of the purpose of the earth is being gathered by the three angels. The earth, the grapes of wrath, etc. it is harvest time.