As for the "mean streak" question, Faulk definitely has that aspect to his game, where he's had enough and just hulks out. The fight he had with Lupul a couple years ago is a good example, Lupul took a swipe at him away from the puck and Justin flipped out and gave him a well-earned beating. That thing with Weiss is another good example, Faulk won't look to start stuff but push it too far and he'll step in.
I could see Slavin develop that same sort of thing, especially if he continues to be a 24-25 minute type. If you're on the ice that much as a d-man you kinda have no choice or people will start trying to take advantage of you, and Slavin doesn't seem like the kind of guy who's happy to let anybody get the best of him.