I've figured out how I'm going to handle updating the plot to keep things moving.  I will wait until at least 75% of the players have responded to my last post (unless a single post makes specific a request for further information or undertakes a "key event" that will immediately affect the situation) before updating.  That means, with five of you at the moment, four of you will have to contribute to the situation before I advance.  When Elandra joins in, that will increase to five out of six needing to contribute.  This may have the effect of making the story advance slowly, but I hope it will keep you all active and involved.  Does anyone have any objections or suggestions on this point?