An Executive Order only applies to the Executive Branch. It is not a general law.
Not exactly accurate. Some Executive Orders do have full force of law. IOW, they become US law. Others, do not.
Remember, in one of the most famous and controversial application of an Executive Order, Truman tried to nationalize the Steel industry in 1952. If the Supreme Court hadn't ruled such a order unconstitutional, it would have been US law.
Also, Congress can undo Executive Orders with bills they pass in both Houses. If the President were to Veto such a bill, the Congress would have to override the Veto with a 2/3rds vote.