The yarn suggested is the premium acrylic known as Caron Simply Soft yarn. This yarn flows with you and makes for excellent wearables.
Depending on the size, the length can be customized by you but is sized at 17" to 22". Wear it long enough that make you feel comfortable. You will want to wear something under it to maintain your privacy. You know what is best for you.
There is basic shaping properties for this skirt and crochet diagrams are available in the downloadable pattern.