Answer:
1. Germany was hoping to form an alliance with Mexico so that they could convince them to declare war on the United States, therefore distracting them from the American war efforts in Europe and in the Pacific. If they had a war in their own "backyard" so to speak, then they would be more concentrated on that and Germany might have a chance to win the war.
2. The United States used WWII to get out of the Great Depression Era by quickly militarizing, producing weapons, and providing supplies to Europe. This encouraged the economy to grow, making the U.S. economy powerful in the market.
3. Germany offered to give Mexico U.S. territory in return for their loyalty and declaration of war against America.