Answer:
1) True - Regional economic integration results in trade agreements. The first measure that those trade agreements usually take is reducing or eliminating tariffs among countries. This is called a customs union and is the most common type of trade agreement in the world, with each continent having several customs union within it.
2) False - Asia does have several trade agreements among different countries, but the continent as a whole is still largely desintegrated. Trade flows between the Middle-East and East Asia have still a lot of room to grow, as well as trade between India and China. It can be argued that by far, the continent that is most economically integrated is Europe, with most of European contries belonging to the European Union customs union.
3) True - As explained before, a customs union is the most common type of trade union, and simply consists in the adoption of common tariffs, or the elimination of those tariffs.
4) True - A common market union is a step ahead of a customs union. It homogeneizes trade policy, regulation policy and production policy among the signing nations. The European Union is a common market union.
5) False - The technical definition of an economic union is the sum of a customs union and a common market, so it cannot be argued that either one of the other entails more market integration.
6) It can be True because the European Union includes common tariffs, common market, common regulations, and even common monetary policy. However, it could also be argued that it is False because it could be integrated even further (for example, fiscal policy could be centralized)
7) True it is difficult to coordinate the interests of many different countries, this is why the World Trade Organization exists (which is not a trade agreement, it's an institution overseeing some fundamental aspects of trade), and also why the TPP (Trans-Pacific Partnership) Trade Agreement ultimately failed.