Abe, it seems what you're looking for is Dataset Explorer - this is where Family and Part attributes are defined. After you copy the S-G22-SlabConcreteprecast part, in the new version turn Fill off and Hatch on using Parts View: Cut Patterns.
But as Marc mentioned, it is best to maintain your custom parts in a separate XML file(s) so that those changes are not overwritten when the product is updated. Search the delivered help file for "Part and Family System" and "Dataset Explorer dialog box" for more information.