5. where did the Babylonians live before invading Mesopotamia?

Before invading Mesopotamia they were living in todays Syria.

Explanation:

As Mesopotamia was the most developed part of fertile crescent many people and tribes wanted to conquer it. The conquers usually came from the North. The similar thing happened when the tribe Amorites attacked and conquered Mesopotamia. They established a couple of cities, including Babylon, which become a capital of the Babylonian Empire.

less available tax revenue

this basically means that when they get money from taxes wirth having a lower gdp they get less then what others have with a higher gdp