I think your points 1,2, and 3 are the most critical. Along with #3, I want to decrease the time of the voting window.

How long does it take a piece of content to propagate to 90+% of its reach? Less than two days. People share content very quickly, and there are some adjustments for different time zones in a global market. If you look at any other content platform you won't find old (2+ days) content above the fold.

So, change the voting window to 2 days and that allows your power down time to be shortened to 2 days + some number of blocks.