Article II of the Constitution states that the President of the United States is also referred to as Commander in Chief. Commander in Chief isn't just an honorary title either, POTUS is the head of all branches of our standing Military (US Marine Corps, US Army, US Navy, US Air Force, and the Coast Guard)
The president can use Executive Privilege to keep their presidential duties behind closed doors. Executive Privilege can and has been used effectively by several US presidents including George Washington, Barack Obama, and the current POTUS, Donald Trump
The Federalists saw the addition of the Bill of Rights to the Constitution as unnecessary. The Federalists believed that our Constitution was a fine and proper addition to the Declaration of Independence and a Bill of Rights was pointless as the Constitution was simply, just that, enough. This was the common Federalist mindset.