The clear is nestled into the frame so it's a solid one piece build.
Dunno....regular plastic?
Doesn't scratch too easily however, it is plastic, so any sharp object will probably leave some marks.
If you buy the case from Otterbox, they'll include the holster along with your order. If you buy it here, usually there is a form on their website where you can claim one and have it mailed to you. Worst case, you'd need to contact their customer support and request the holster.