When Europeans came to the New World, Native Americans were immediately exposed to fatal diseases that Europeans were immune to but they were not. So, if the Native Americans weren't already dead from smallpox and other deadly illnesses, Europeans' thirst for power would kill them. As the New World expanded Europeans met more Indian tribes and would kill them to pave a way for European colonies.
Yes, the growth domestic product measures the amount of goods and services the United States buys and sells as a nation. Therefore a large GDP means the United States economy is expanding which provides lots of economic opportunity for our citizens.
Communist countries. So countries like Russia, North Korea etc
Real home prices were not shown which fluctuated the economy
(Hope this helps :D)