Growing Successful Communities
Anton,
All great questions. Check out the last section ("The Current and Future of Content") of Michael's Wu's Health Factor 2: Content blog.
Hello ac, thank you for your inqiry.
We do plan to implement some drill down capability at the various community hierarchy in our next version of CHI. This was actually discussed at my blog. 
http://lithosphere.lithium.com/t5/Analytic-Science
We intend to have this drill down capability for 3 or 4 of the health factors. But computing CHI for each board is probably not as useful. Moreover, it may not be a well define quantity, because some of the health factor (say member, for example, which is measured by registration count) is not strictly associated with a board, or category. However, you can drill down and see the interaction, responsiveness, liveliness, and content, and maybe traffic for each category to see which business unit is getting the most interaction, which is getting the fastest response, etc.
