"Anything you download or upload from/to others will affect your ratio"
I totally forgot to mention freelech torrents, so just in case your not familiar, when a torrent is marked as freelech, the downloaded bytes will not count towards your stats/ratio.
That's true only during freelech time, if the freelech ends in 24 hours it means you have 24 hours to finish the download for free, after this period any download bytes will be counted.