That might be a good idea for the former, though it means that only players would participate almost. Also, I believe you can actually ask this on the already existing thread of Matsuri
As for the later, it was already created since the game release.
Check
this link. Since the game doesn't have anything to do with higurashi (not a prequel/sequel/spin off of Higurashi), it shouldn't be created in higurashi sub-forum.