Add custom fields to the Support System support ticket form?

I have a multisite setup with seperate sites for:
1 - I would like to add a way to designate the originating site with a drop-down list or from the originating link location.
2 - I would like to add categories with Sub-categories for their selections.
My goal is end user support rather than sub-site admins. End users of the store will have much different questions than those trying to take a course.