Catering for Multipe Audiences

I'm developing a course that is intended to be viewed by people in four different job types. Some of the slides are common to all, some have alternative slides depending upon job type, some users skip certain slides, etc.

Early on in the course I ask users to click a radio button which stores their job type in a memory variable. I then intended to create routing dependent upon evaluating the variable at appropriate points.

There are a couple of issues I'd appreciate advice on from anyone who has done this before:

1. Should I set up parallel tracks (scenes) for each job type that they follow to the end, or is it best to avoid duplicating slides? If so, is it feasible for a user to jump in and out of the main scene several times?

2. As the different user types would have different items in their menu, is it best to only display section headings? If so, there would be very few items common to all in the menu.

Unfortunately producing four different versions of the course isn't really an option, as they want only one course listed on the LMS.

Any thoughts/help appreciated.