The best ones are "Jaksta Media Recorder" and "Replay Media Catcher". If you google them you can find cracked versions ready to download and install  ;D

Yes, I always do that. I never remove a torrent until I haven't seeded it enough, even if it's a torrent I haven't downloaded in full. Considering all the above I finally think it doesn't matter 10GB or 100GB, every way has its advantages  ^-^

I think 10GB parts would be better. That way you can choose what parts are you most interested in. I know that you can choose what files you want when activating a torrent but then it will appear in the leecher list forever because it isn't completed while you seed it…