Here's a great description of contents and how to manage organic 'bedding' in a run or coop...and there's a great video of what it looks like.
http://www.backyardchickens.com/t/1037998/muddy-run-help-please#post_16017992
I'd definitely go with 1/2" HC on bottom 2'.
Weight should be an issue if coop is stationary.
Hey I think you need to clear your editor of draft text??
I keep seeing that bottom text (under netting pic) in several of your posts?