Delete the torrents once they stop buffering your ratio and jump on fresh ones. Just keep the popular ones.
You need to jump on torrents as soon as there released, the more seeders on a torrent the less upload you will have.
Priority will go to people that have faster seedboxes than you so don't skimp on the cost of one.
What-cd torrents will not jam up your seedbox because they are not being downloaded continuously like on other trackers.
Don't mess around to much with the settings on your seedbox as they are configured to maximize the performance of the box, altering them can be more trouble than it's worth.
As for the amount of seeders and leechers, it may show a certain amount but the fact is some maybe offline and some are only partial downloaders.
This means they have only downloaded some of the torrent and started seeding, these torrents can hurt your ratio if you download them.
The best way to not get caught out by this is to check the peer list of the torrent before you download it and see how many peers are actually active on the torrent and how many are just partial downloads.