Several questions about classes and courses

I have installed opigno and playing around with classes, courses and lessons. The platform will have students from many colleges. Each college will use many of the same courses but some will be specific to that college. My idea was to create each college as a class, assign students to that class and add the relevant courses to the relevant class. All class and course settings set to private. My first problem when testing this is that I have to add students to both the class group and each individual course group. Am I missing a step here? When I do this the student is able to unsubscribe from the group class or course. Is there a way to turn this off? Also in course settings if I disable tools for user (from my part targeting this at students) they are also disabled for admin? On a completely different note whilst setting questions in a lesson is there a way to pick up a url to another question and embed it to create a decision based path through them rather than just sequential? Idea being students pick between a show me pathway or a test me pathway. If they fail the test they are directed to the show me section? Hopefully this all makes sense. Any advice gratefully received