To James Bond, when is it acceptable to kill someone?

To M, sending Bond out to kill for personal vengeance is not acceptable, but sending him out to kill for societal justice is. Yet Bond feels bad about killing when the victim is not a personal enemy. Why?

The third chapter of this James Bond novel is a story within a story and contains no action. What is the significance of the story of the stewardess, Rhoda Masters?

Why is it important that Rhoda Masters is a stewardess, someone whose job is to care for others?

Bond is a killer, and he seems to sanction personal vengeance. Yet, at the end of the novel, Bond does not want to go off with Liz Krest if she killed her husband. Why not?

Rhoda Masters and Liz Krest are both at the mercy of their husbands...