yeah, there's a lot of problems here that I think are going to be inherent in any system that is basically a free-for-all fest. You've covered a lot of them above, so I won't add to those. But there's one less contentious thing that I think needs revising, and that is the 7 day payout window. What happens when a post goes viral after a month (or even 8 days)? The author gets nothing for it, other than I'm assuming some reputation points. What i'd do is have a sort of reverse curation that kicks in after 7 days. By that I mean that any comments made after the 7 day mark pay a 25% curation reward to the original author of the article. After all, it's his/her article that is allowing this viral explosion in comments to happen. They should get some of the new rewards on offer for that.
i do agree that it is a kind of strange that after 7 days a post loses it's value, while people can still upvote the post. It's also strange that after 7 days you can't resteem it anymore.
Wow, I didn't realise that about the resteem limit. Crazy. The idea that a post only has value for 7 days is ridiculous.