Actually, you can download more than the default ratio if you have a fast internet connection then you can download everything before the tracker update your ratio
Here is the official link, it is a standalone software. It does not depend on any bittorrent client. Just load a torrent, and change some setting and start "seeding", by default values are very low so adjust them for your network speed, don't try and put absurdly high value or it might insta-ban your account on ygg
I use yggtorrent for all my linux isos needs, but I also use ratiomaster to fake seed as every torrent I ever downloaded never gone up to 0.1 of ratio... so fuck them and fake ratio is the way anyway...
Yes, just switch your user agent with an extension.