1. Jellyseer is what I use, also allows others to request stuff
2. I download via torrents, automated with the *arr suite
3. My seedbox, fast speeds also help with my ratio
4. Jellyfin, just because i prefeer FOSS
5. Jellyfin covers that, if i happen do delete some show then Jellyseer still remembers if i finished it or was only partially done

Lots of seedbox providers offer all these tools with their boxes so you dont need to host anything