Check out Joey the Hitman by David Fisher. That goes into some pretty good detail about a hitman's exploits and isn't all bullshit like Kuklinksi. As for the other two points...you got plenty of those guys who seemed to enjoy it. Anthony Casso comes to mind as a sick puppy and Nicky Scarfo two. They were an underboss and a boss. Then you got the guys like Tommy Pitera, Mad Sam DeStefano, and of course Roy DeMeo. There's also Irish sickos who were pretty prevalent in the torture area like Whitey Bulger and Jimmy Coonan.
