You provided great and insightful ideas. I agree with you that the core problem is false curation which include circle-jerking, voting bots, over self-evaluation, etc. I think that these curation behaviors generate Steem token at near zero cost and presse down the price.

Especially, I like your second fix, while we need to consider specifica numbers. IIRC, you meant downvote should be asymmetrically applied, and curators are panelized more than authors.
I think it can effectirvely destruct voting bots (cool!) and have same disadvantages to self-voters of circle-jerkers because the total(author+curator) decreased reward is same.

Make curation great again!