icing sugar is confectioners sugar or powdered sugar or sugar that is very fine combined in its' packaging with corn starch.
Crisco is shortening that is solid, white, thick and not necessarily made from animal fat but rather vegetable fat.
Crisco is one of the top sellers here in the states but any brand would do. personally and I'll go on record here, I prefer butter to crisco in peanut butter cookies but the solid shortening does produce a very tender cookie which I think is aided by the use of the confectioners sugar/aka/icing sugar in this particular recipe... hope that helps you understand the ingredients more.
...Trials travel best when you're taking the transportation known as prayer...SLRC