Question: What were the last lines of the movie?
Question: Does the ending mean that the policewoman gives up on her hunch?
Answer: No, she didn't give up. When "Smith" called Detective Atwood, she realised that it was a different voice (Brooks) and that the police may have fingered the wrong person. She was not the type who would let this go.
raywest
Question: What type of personality disorder does Mr. Brook have, is compulsive killing part of it, and is it really genetic?
Jason RileyChosen answer: It sounds like Dissociative Identity Disorder. And I think compulsive killing is something he chooses to do, and not connected to his DID; and from skimming the article, it doesn't appear to be genetic.
Cubs FanQuestion: What does the ending mean? Does Brooks kill his daughter before she kills again?
Answer: There is no clear meaning about the ending but he does not kill his daughter, Jane. When Brooks dreams that Jane murders him, it seems to indicate he fears she is destined to become a serial killer like him.
raywest 
Answer: Marshall's line was, "Why do you fight it so hard, Earl?" Earl Brook's was, "God, grant me the serenity to accept the things I cannot change, courage to change the things I can, and wisdom to know the difference. Living one day at a time and enjoying one moment at a time, accepting hardships as the pathway to peace. Taking, as He did, this sinful world as it is and not as I would have it, trusting that He will make all things right if I surrender to His will, that I may be reasonably happy in this life, and supremely happy with Him forever in the next. Amen."