The passenger should be treated as a "passenger". Think about the brief you get on a typical airline - how to use the seatbelt, how to use the oxygen etc.
Apply that to a light aircraft - very similar i.e. seatbelts, door latches.....perhaps include where the fire extinguisher and first aid box are. Personally, I wouldnt include anymore....and i certainly wouldnt be speaking about engine failures etc....they are a 'passenger'! My local CPL and IR examiner would chin you one if you mentioned anything about engine failures or icing conditions etc!
