Many plastics will degrade if exposed to direct sunlight for long periods of time. I have not worried about this for my equipment and it has been in the sun for 8 years with very minor degredation. If you are concerned you could either cover the area or apply a good car wax with a uv protector. I don't think it the best thing to enclose the area as chlorine fumes will collect around the ground and be trapped over time and eat away metal.

As for taking equipment in for the winter I would not think you really need to do that. Blow all the water out and if you are concerned fill it with the pink RV antifreeze. That stuff is good for either -20 or -40 degrees. I do that with my pumps and skimmers each winter and have never had a problem.