Ok, to unroll, it's easier with two people - one on each corner of the blanket, pulling it off the roller as you walk to the oposing end of the pool - you can do it with one person, but may have to run from side to side a couple of times, when unrolling leave it on the roller and pull it off as you walk to the opposite end, it should go smoothly. The cover should stay on over night to keep the heat IN the pool.
The cover should stay on the pool if evaporation is a concern during the day.

Since you have a clar cover, I would leave it on the pool during the day.

In your case, take it off only when swimming.