Rehearsing conversations you are going to have with a person can be a great way to prevent saying things that will get the person upset.

Other authors of self help books have told about how they had inner advisors that they discussed things with in imagined "meetings". As long as you know the difference between the inner characters and the outer characters and do not confuse them or try to explain to the people in your life about the inner characters, you should avoid confusion and misunderstandings.

I am not sure people would in general say it is normal, but it is effective but should be kept quiet in my opinion because there are people that cannot tell the difference between outer reality and inner conversations that "normal" people label unstable. I know you are not one of them, but telling people who consider themselves to be "normal", whatever that is, is bound to create controversy.

I would say tell us at Psych Central about that. Do not tell your boss or your neighbor. Other people see things as black and white and would probably not understand.