Correct usage/terms

this would suit a younger, far less cynical audience
this would suit a younger, far less cynical, audience.

A sort of, what the audience doesn't notice, won't hurt them attitude to the screenplays.

(Is the punctuation correct in this sentence).

One story is complex and the other quite dull. Yet both are scary.

(do I need 'stories' if the subject is obvious) Yet both stories are scary.