Faith in socialism, capitalism or communism prevents the rise of fascism because it combines aspects of these things but is different from them all. The idea that democracy is failing can help it rise. Hitler exploited the instability of Germany's democracy and the failure of the coalition governments to push for total power, presenting the idea that Germany needed a 'firm hand' for 4 years to get back on steady footing.
Because of the enforcement of laws on the republic
An advantage is that it takes way less time to do it than to create a formal treaty since the President would not need consent from the congress for an executive agreement. A formal treaty can, however, last longer because it is more difficult to cancel, so if it's good, then it is also safer for it to be formal.
Larger states didn't feel it was fair for the states with smaller populations to have equal say in government
