What is the difference between a free trade area and a customs union? Between a customs union and a common market? The United States and Russia belong to an economic bloc, how is this the case? What...

What is the difference between a free trade area and a customs union? Between a customs union and a common market? The United States and Russia belong to an economic bloc, how is this the case? What are the stages of regional integration? Why are countries likely to go beyond a free trade agreement? Why might a corporate based outside a bloc choose FDI as their method of entry into the bloc?