As to the forum activity, I've seen it ebb and flow since I've been active here (I think I started coming to the forums when you were still posting new riddles regularly. I think one of the first riddles I worked on here was one of yours but I can't remember exactly which one.) My feeling is that it depends on how many riddle writers are active. I've never been good at writing the riddles so I haven't contributed much on that end. But it seems that the forum will go through spurts of new riddle writers which will generate a lot of activity for awhile, at least until the writers either run out of riddles or move on to something else.
Thanks for the input. However, your answer didn't germinate. : )