Wow, I thought I'd get a lot of replies on this???
As for the windshield, there is no separate part number. Builders get the whole canopy as one bubble, then cut it in two. You'd need to order the whole plexiglass bubble or perhaps one that is damaged towards the rear.
Not true. You can order the windshield separately. I bought one in Feb. from Van's. The item on the order was "C-601 Slider W.Screen Slider Screen Only" $425 to Van's plus ~$80 shipping to Airplane Plastics for the drop ship. It seems the process has changed over time but at least in Feb. 2016 you could not order directly from Airplane Plastics. Had to go thru Van's.