Seems a reasonable list to consider.
I like the opt out for passive return, with a trim. Would be interesting to think through if it would be better for the 25% to be burned or returned to the curator pool/ or author pool.
5% burn for instant powerdown would be a good tool, as while I don't think people will use it that much, I also think that it will force people to think about their stake more and what it means to them.