Answer to Question 1
The degree to which the drugs have accepted medical use in the U.S., their accepted safety for use under medical supervision and the degree to which they have potential abuse liability. Schedule I drugs have no accepted medical use in the U.S. and high abuse potential, whereas Schedule II - V drugs have accepted medical use and progressively have less abuse potential.
Answer to Question 2
The FDA does not have any authority over the practice of medicine. There is no federal law that prohibits physicians from prescribing an approved drug for anything they choose, although some states may place restrictions on what certain drugs can be prescribed for. For instance, a drug approved as an anti-seizure medication may be prescribed as a mood stabilizer for a person suffering from bipolar disorder.
