Powerdown can't be shorten to 3 days when the post payout is 7 days, that will bring serious issues. 7 days is the minimum but I agree with many witnesses with the 4 weeks period.
Downvotes are needed to control spam, that's why they were implemented. For years we had a serious spam/bidbot problem that was strangling all the hardworking people trying to get their content to be seen. Downvotes cleaned the place of all that and its helping to control abuse, giving everyone a fair opportunity to have their stuff seen and voted.
If making money is what brings you here then you have to consider those two.