To answer my own question after using it:
1. It depends on the resort; some Snow25 passes can be loaded when you purchase the ticket, while others cannot.
2. If you were not able to load the ski ticket onto your SwissPass, you would have to go to the ticket control desk anyways, where they will either a) load the ski lift ticket onto your physical SwissPass, or b) issue you some other ticket/card to use for the lifts.
Hope that helps!