I think you have some great ideas. It's completely different from how I approached it. My approach was to create a community (Blockchainpoets) that required posters to comment twice as they made their post. Honestly, it kind of failed, but a lot of that is due to my failed execution. I do think it would have done better if I had some backing of sorts to incentivize people to post in the community.
I was also thinking of rewarding comments in the community, but I run into the problem of dust votes. @dustsweeper might be a possibility for solving this issue.
It's an interesting problem for sure. It's good to consider different ways of attacking it.