"I'm going to rename 5 to 4 and 4 to 5. If you can't keep that straight when dealing with this community, but not the rest of the world, it proves you're an incompetent dilettante and we can safely ignore you."
Yes, very reasonable.
Yes, very reasonable.
B) You have the logical entailment flipped. Know arcana => in-group. ¬ in-group => ¬ know arcana. It's designed to reject out-group members efficiently, even at the cost of a high false positive rate.