Thing is cats don't protect you, dogs do, but I can't disagree with you when you say cats are friendly and loving, they very much are. And mine are boisterrous too...I wish they do one tangible thing of protecting you like dogs, but well, you can't have that...
I heard the purrs have good healing powers, not very sure, I get purrs at times, not that often, when cat garu sleeps in my lap, not often.