I will be looking for content that is useful and is easy to find on the actual forums we will be covering getting started and mining, then their will be signals and betting with points what you earn from posts, which will eventually can be converted to bitcoins to the users but still on the drawing board with that idea and how to implement where everyone happy.
So, a user can get paid by posting trading tips or something like that? You'll need a considerable amount of time to scroll their post.
Instead of doing that, maybe add a similar system like merit and a specific rank where the user's sig space can display ads. From that space, your forum ads will be displayed and the user get a portion of the payment. This might get abused but after you get some traffics you could change it anyway.