This is just my opinion, but if I were to make the whole Beginner/Professional layouts thing, in the Beginner layout the following settings would be visible:
- New cards per day and review cards per day
- Leech threshold and action
- Burying siblings
- Stuff related to the timer
My reasoning is that even if you have absolutely no idea how scheduling works under the hood, you can still understand these settings.
As for FSRS, only the desired retention would be visible.