The title change is unnecessary. Henrik, I did laugh at your comment that it sounds like the musical version, CARNAGE!
Polanski has said that the whole film (or a majority of it, can't remember exact quote) takes place in the apartment so I imagine it's going to be very claustrophobic, tense, and hopefully funny too. The only person I'm still not sold on is Jodie Foster just because I've never seen her being as hilarious as Marcia Gay Harden was in the stage production, but Polanski is a master of getting the right performance out of his actors.
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"