I'd have to see a replay, but I thought RJ had lost possesion of the puck a second or so before the hit and Campbell would not have been able to stop his momentum.
Clearly Campbell intended to hit RJ, but I'm not sure he expected RJ to have his head down. It was a brutal hit, and it shows how the speed of the game can create such a violent collision. I totally understand the feelings of Flyers fans.
Regarding your second question, you do make an interesting point, but you almost consider an elbow as a weapon moreso then a shoulder (even with the equipment).