[HOE] A question about Servitors (possible light spoilers)

My question is three-fold: Do servitors know thier weakness (the one thing that can kill them)? Do they know they are Pure Evil on a Stick(tm)? And can they be stunned?

I have always ran the Big Bads as if they knew they were evil and didn't care, that their immunity: all meant exactly that. You can drop a GR Bomb on thier head and they'll look at you, spit, and growl "Not enough Gun". And I've always played that they know what the one thing is that can kill them. Now, I understand PEG has been a little wishy-washy on this subject. For example, Desmondia (the Infestations big bad) knew she was evil but kept the one thing that could kill her in her freezer. Kane (from the IMAX theater) probably knows he's bad, and definitely knows the one thing that can kill him. Modeen knows because if you read the adventure, he's got a back door escape route. The Boise Horror knows as well cuz it trys to get away. Whats the official rule on this? Thanx for your help in advance. Shawn.