I Have A Questions About The TV Show Supernatural?

The colt can kill all supernatural things, they just haven't had an occasion to use it on an angel yet. And yes Dean was in hell for the equivalent of 40 yrs but i think it would take alot more then that. Like 1000's if not more. Also Dean admit's that in the end he started to torture people but he was pulled out not to long after that. If he had continued to torture people for 100's or 1000's of yrs he would have lost the little humanity he had left and really become a demon