Imagine a spherical creature the size of a 18 wheeler without the trailer, how does it moves in search for mates? Would rolling around be easier and consume less energy than bouncing or wiggling? How can it prevents from feeling giddy when it rolls to safety in a short burst and keeping balance on level ground? Last but not least how does it prevents itself from losing too much fluid due to the surface area vs it's mass?
A spherical creature can move by tilting its balance. It simply needs to contract its muscles to shift some of its mass, the resulting imbalance creates movement due to gravity pulling the creature. By repeatedly doing this your spherical creature can accumulate speed by barely moving.
A spherical creature needs proper grip on its terrain. For reference look at the way earthworms move. Their segments are lined with setae (small bristles) that grip on the ground while they slide forward. By using this method your creature can grip a surface and and tilt its body to grip somewhere else and move. This also serves to stay still and grab objects.
Rolling is indeed very energy efficient, however it only works on stable ground. You can roll down a hill but climbing it would be very difficult.
Rolling requires proper balance and since your creature is made for rolling it would not feel dizzy. In fact its sense of equilibrium will probably be very developed. We sense our center of gravity using the vestibular apparatus in our inner ear.
Its mass is greater than its surface area so it won't lose fluid. Due to the square cube law if its size increases two fold its mass increases three fold. Since your creature is spherical it has the smallest surface area possible. The only real risk of losing fluid is spilling its guts, sweating or bleeding.