First I'm kinda confused. I'm concerned if these 2 questions bring the same nuance or not... "Isn't he young?" and "He is not young? / He isn't young?". Both sounds quite different on how they imply the speaker's perspective.
I believe that these 2 questions are different...
The former just asked "He is not a doctor?" and "There is no class?", which imply that the speaker wanted to clarify the negative situation.
The latter is explanatory seeking. "Isn't he a doctor? (I thought he is!)" and "Isn't there a class? (I thought there is!)" imply that the speaker wanted to clarify that their first stimuli received are wrong.
Here comes い adj.
Here the guy is asking "Isn't it Smelly? (It's stinky!)", more like "It's stinky, right? (asking for the listener's agreement).
this is translated as "you aren't scared?"
and furthermore if I add の after じゃない, what changes?
授業があるんじゃない vs 授業があるんじゃないの
does the latter just mean more explanatory seeking?
The whole ordeal confuses me. If indeed those 2 questions at the beginning differ, can someone explain to me every formula in constructing negative questions with/without の that gives out specific nuances?