Just a brief suggestion on how to address the issue of room culture in terms of drawing a line and generalising the point:
With respect to developing an individual culture, chat rooms enjoy the same freedom and limitations as Stack Exchange sites.
From this we could derive for example:
If you ayour comment would be flagged as offensive on any Stack Exchange site (taking into account the context, if necessary), it does not belong in chat either.
If a discussion digresses to a topic that would be inconceivable to be the focus of a Stack Exchange site (even if it gained enough support on Area 51), it should be put back on track.