So you are saying that the congress has the constitutional ability to pass on the power to the Pres alone?
Congress must authorize a military campaign. That much is clear from the Constitution. How they word that is irrelevant. Passing it as a Resolution is the way which is most obviously in keeping with the Constitution.
The Constitution doesn't really provide strings for withdrawing that power, although they can certainly cut off the budget for the soldiers.
But, yes, they MUST pass that power to the President. It's required. Even the Founding Fathers knew that Congress couldn't run a war.
Im more libertarian then you but the thing they are most wrong on is foreign policy. I don't see anything in the constitution that says a declaration of war was neccasary to wage one. Thomas Jefferson waged an undeclared war against Tripoli, Tunis, and Algiers.