I did not look at the picture before I posted last time. If you're uncomfortable sewing make a cover with velcro, there is that fabric glue that will eliminate the sewing portion. I really wouldn't use plastic though, that will really make you sweat, there is thicker fabric, like the stuff you change baby's on, almost water proof.

I remember something I've seen on Martha Steward that I do with my feather beds in the summer. Put like 1 part vinegar 3 parts water, spray the thing and put it in the sun to dry, something with the sun, vinegar and feathers.

For spot cleaning I would use the Resolve fabric cleaner.