Interesting thoughts, but I am sceptical:
1. Increasing curation rewards
Assuming that your measures would work and it would be easy to find good content on trending since it gets rewarded highly, higher curation rewards would disincentivize voting on this content in most cases. If I see a great post on trending or hot, voting on it will get me less curation rewards than voting on a mediocre post that has next to no rewards yet but will have some rewards since the author has loyal followers. Non-linear curation rewards would improve this situation, but not change it. Under the current system, this is the reason why I have set up a large part of my votes as autovoting for my favourite authors - voting at 13 minutes gets me much higher curation rewards than selectively voting the best content in my feed once a day would.
2. A non-linear voting system
Non linear rewards could be beneficial, but assuming there would still be vote-sellers, non-linear rewards would make buying a lot of votes more profitable - even more, curationreaper bots would vote before the vote-sellers do to increase their curation rewards
3. Downvote Pool
Voting power for flags coming out of the upvote pool is only one reason why there is so little flagging. The more important part is the fear of flagwars - I would love to flag many vote-farmers, but I know that this would likely result in them flagging me back. An anonymous downvote pool could be the solution there - if the whale I flagged can't see that it was me who flagged him, he can't flag me back.

Having been on the platform for nearly a year, I am at a point where I am sceptical if the rewards system can be fixed at all without leaving loopholes for farming rewards by abusing the system. The only solution I can see is that at one point delegating SP would become more profitable than voting (be it self-voting or reaping curation rewards) since so many dApps would want to rent SP to reward their users. For them, distributing their upvotes to the best content would be in their best interest for growing their platform.