The unmagnetized pieces of iron would be randomly pointing to directions, this is true because although influenced with the magnetic domain, the direction of the unmagnetized iron field of attraction is not uniform or does not have preferred direction.
We are asked in what manner can one make the motor run in reverse. One way to do so is to flip the magnet on the other side so that the opposite charge faces to the motor. The magnetic field induced by the magnet to the motor results to a reactive force opposite to the induced motion.
I would say downstream since the stream can push your boat, then you would have momentum and would just have to row towards the land.
