An ampere-turn is the unit of magnetomotive force, the work required to carry a magnetic monopole of unit strength once around a magnetic circuit.

Yes. All magnets of north and south poles. There is no such thing as a magnetic monopole.

Yes. All magnets of north and south poles. There is no such thing as a magnetic monopole.

magnetic field is a region of space where a north magnetic monopole experiences a force. The direction of the field is by definition the direction of the force on the north end of a magnet. Since most texts contain diagrams of magnetic fields they will not be reproduced here.

Probably not. The magnetic monopole, as it is called, has never been observed. Some theories predict the possibility that they exist, though.