#3 is asking you what freedoms does the Constitution give us. Think about the 10 Amendments. List some of those rights and freedoms. For example, Freedom of religion, right to bear arms, etc.
#4 It is considered the Supreme law of the land because we all (50 states) have to follow those laws.
#5 The Constitution states no one person should have all the powers. For instance The Senate could reject a treaty negotiated by the president if they did not agree with the negotiation.
#6. I think it's because they have to go by the Congress then (if approved) it is gone to the states to be ratified by 3/4 of the state in ten year time period. If not then it;s not add or amended.
Hope this helps :)