Regarding the current 7.3/4 LSA course, there are no restrictions on the development platform as long as Pega 7.3.1 is installed.  You are free to use a PE or VM.

I would question the need for snapshots. There can be multiple questions based on the same starting application, i.e., an improved version of the Booking application that is used in the 7.3/4 LSA course.

There is very little possibility that one question's build would overlap and affect another. For one question you could add patch versions, for the next question you could start within a new minor version. It is fine to create new ruleset versions as well.

We realize it can be challenging to package the Booking App's Application rules (Booking, Hotel, FSGEmail) in the state that corresponds to the solution to each question.

It is acceptable to define new Application rules built on the existing Booking applications (Booking, Hotel, FSGEmail). If so you would also need to define new Administrator Access Groups plus add those AGs to your Admin.Booking operator record.  Depending on the question you would also need to do this for the actors needed to test the application.