Never pulled one with horses, but have some experience with a small tractor. You can do fairly square corners just by turning tractor fairly tight at the corner, at just the right time. Need to be careful to keep out of the reel. Small wheel will pivot, or even go backwards a few inches.
Bull wheel is mounted on a vertical rack. A crank provided with the machine allows operator to crank wheel up/down. Probably want to crank it down while it is still supported by transport wheels.