Leg Avenue Women 3Pc Arabian Beauty Off Shoulder Top With Harem Pant n Headband

Is this stretchy like body on?

How do the top and pants close? Zipper, velcro, or just elastic?

Why is there a huge price difference from small to medium?

Does the costume come in a plastic case? If I take it out of the case to try on, is it still returnable for refund?