I think it’s reasonably well understood, but a lot of misconceptions and misinformation exists.
Npc’s have cap that is pretty easily testable by nosing them. and every NPC has a cap listed on http://games.chruker.dk/eve_online/npc_ships.php I suppose it is possible a ship scanner would show an NPC’s cap, but I don’t recall every trying that.
that said, NPC’s modules activate independently of that cap. I believe their repair mods activate on a chance based cycle, along with ewar mods, and then their guns will always shoot.
Now the big question is does the AI have modifiers that activate when getting hit by cap warfare? AFAIK the answer there is no. I suppose you could take a low dps missile ship that just barely has the dps to kill an NPC and time how long it takes to kill with a few different conditions. I’d test a few with just missile dps to get a base line and see how different you can get it due to local repairs, then some more with nos, then some more with neuts. Could also fit a ship with max tank and cap mods and see if a burner ever drops point. And probably worth checking sleepers if you want to go that far.