#2923: inventory, as an optional setting ([Game], show projectile damage).
#3851: Boethia should still speak through the player. Script command "say" bypasses dialogue manager and uses sound manager instead, which doesn't check if the actor is a submerged NPC. Non-scripted dialogue, though, like pain screams, wouldn't be used in such case.
#3921: yes, in
one of Andrei Kortunov's AI improvement pull requests: now NPCs attack based on effectivity (you won't attack a Daedra with an iron sword they are resistant to, but you very much would a helpless 1 level player) of their attacks to the targets they are in combat with, not distance to the targets.