Yes, provided that you possess the necessary equivalency ratings to fulfil the requirements of an instructor crossover, you can take part in the Scubility instructor course.
No, the Surface Buddy and Dive Buddy elements are of critical importance, the instructor level builds on these foundations from this element.
As a non-diver, but comfortable in the water and able to snorkel, you can play an important role as a Scubility Surface Buddy, assisting with kitting up, dive planning, and entries/exits, a role not to be underestimated.
Allow 3 full days to complete the course.