I like the idea that only "photocrew members" can start threads.

I like the idea that registered users can post in those threads.

I don't like the idea of creating a thread with the pictures, then a link for comments...to me that sounds like the "Featured Ride" section.

I would also suggest a well developed set of rules and strict moderation of them.

I would also suggest that "entry" into the 'photocrew' never be closed, because what if one day someone else figures out how to take good pictures, or someone who can take good pictures registers?

Good luck.