Why do you think it is a good thing that the President can just pass laws without approval from Congress?
Yes I was talking to you in my answer. First, I don't have a full understanding of how your Parliment system works, and the role of PM. Your Queen is purly a sybolic position as far as official governement, or am I wrong about that? I'm sure the royal family has considerable influence, but do they have actual goverment powers? Such as passing laws or control of any departments, etc.
The reason I stated Legislative, Judicial, and Executive Branches are becasue each is a separate entity in our Governement, and have a system of checks and balances. The President can not pass laws by himself. Laws are introduced in the Legislature, and have to pass the votes of the 2 houses,(The house of Representatives and Senate). Each state is allowed 2 Senators, and each state is allowed Congressmen according to population. After a bill is passed it goes to the President where he can sign it into law, or Veto the Bill. If it is Vetod, it returns to the Congress, and they can either ammend it for the reasons given, or just override the veto and pass it. A President can only Veto an entire bill as it is written. There has been a suggested law that the President be given powers to "line item veto", which many states allow Governers to do. Also remember each individual state has it own right to govern, so they all have similar systems within each state, passing certain state laws.
The duties and powers of each branch of Governement is defined in the Constitution, as to what the limits of each are. The President has a Cabinet which he assigns, like the Department Secretary, Secretary of State, Secretary of the Interior, Secretary of Defence, + others. These things all come under the powers of the Executive Branch of Government, and within that are powers of the President over the Military, becasue he is the Commander in Chief.
I think the President should be have complete power over the military, which is the chain of command to the top general, who is the President. If the President is fallen, the VP is next to assume the position, but 3rd in line would be the Speaker of the House, Nancy Polosi, and not the most logical to control the military which would be Secretary of Defence (who is not elected).
We have an amazing system, that is both simple, but also extremly complicated, with complicated laws, expecially inturpeting the Powers of the President. The Gulf of Tonkin resolution gave LBJ the Presidental power to commit 550,000 troops to Viet Nam without the permission of Congress. The President would need the approval of Congress for an official Declaration of War.