Well, as I posted,
/mode #channelname +r
would keep out the unregistered troublemakers
/mode #channelname +m
would make the channel moderated, keeping everyone quiet unless one of the ops gave them +v based on whatever criteria you choose. Note that "quiet" includes not being able to change nick while being silenced.
Since you want the generic public able to enter, a #channel key or a system where the ops have a list of passwords for a group of known users won't work.
