1.)why is the rule of law an important principle?
2.)how does the constitution limit the power of the military?

The rule of law is important because it states that all citizens are subject to the law. Monetary status or position doesn't change the law or being subject to it. The constitution limits the military's power because the president is the head of the military. He or she is the one who can declare war. Also, members of the military arts still subject to the law.

The rule of law is the legal principle that law should govern a nation, as opposed to being governed by arbitrary decisions of individual government officials. It primarily refers to the influence and authority of law within society, particularly as a constraint upon behaviour, including behaviour of government officials.
The phrase can be traced back to 16th century Britain, and in the following century the Scottish theologian Samuel Rutherford used the phrase in his argument against the divine right of kings. The rule of law was further popularized in the 19th century by British jurist A. V. Dicey. The concept, if not the phrase, was familiar to ancient philosophers such as Aristotle, who wrote "Law should govern".

Rule of law implies that every citizen is subject to the law, including law makers themselves. In this sense, it stands in contrast to an autocracy, dictatorship, or oligarchy where the rulers are held above the law. Lack of the rule of law can be found in both democracies and dictatorships, for example because of neglect or ignorance of the law, and the rule of law is more apt to decay if a government has insufficient corrective mechanisms for restoring it. Government based upon the rule of law is called nomocracy.