On the casual observation front, I have never seen any evidence to support that when you are outside of the draw distance of any particular chunk, that anything particular happens there. I have left areas and returned and found what I guess would be mobs frozen in time, as if they had never moved very far from their positions when I left them behind. I have found yellow and blue bags as the morning rose without ever having actually killed any zeds on the road, which supports a hypothesis of mine that they were wandering ferals, which I think die upon the morning chimes.