I have not personally been involved in organizing the mayoral hustings - I think Nigel Desborough, who I believe is currently chair of the Lewisham Borough Deans (as well as of Churches Together in Sydenham and Forest Hill) has been in the lead. Indeed, I understand that he rather than Jon14 (I know Michael will find this disappointing!) is to chair the hustings.
I'm afraid I don't know the answers to Michael's other questions.