Here are some more threads to be mined for info. They're heavy on the UK perspective, but not purely so. The "folk club" scene often is performance oriented, but there are other more informal/inclusive sorts of gatherings under the umbrella of that term as well. (So it may take work to find what you're looking for!)

Help: Running a Folk Club. (Aug 03)
Starting a folk club (Dec 05)
Starting a Folk Club (Jul 07)
Starting a Folk club (Aug 09)

Another recurring topic, and certainly worth addressing:

Bad Manners at Sessions, Singarounds (Apr 03)
Worst singaround/session rudeness ever? (Aug 06)
Versions of songs, and etiquette (Nov 07)
Musician Rudeness (May 08)
more session rudeness (Jun 08)
Folk Club Manners (Oct 08)

an outside link I came on: Lombardy folk music stuff ("which has lots of hints and tips on floorsinging, running a folk club, breathing, session etiquette and suchlike")

~ Becky in Tucson