As one of the top comments said Stremio+RealDebrid is just awesome, install on your phone and cast to your tv or install on lets say Nvidia Shield which is what I do, phone while traveling. Can use your RealDebrid account inside Kodi using The Oath or Seren add ons but I think you will get the same torrents/quality as Stremio in terms of torrents but if one goes down you have a backup of sorts.
I have a FreeNas server with thousands of dollars worth of hard drives full of linux ISO’s and I don’t even turn it on as I can find everything on Stremio although if you find an obscure doco that only one person intermittently is seeding then downloading the old fashion way is the way to go.
The only downside I find with using Stremio is audio lipsync issues which drives me a bit crazy. I usually try another torrent and cross my fingers.
I have a Kobo and use calibre to manage my books. I don’t sync online it’s just plug and remove what I have read and upload my next lot of books that I want to read. My Kobo currently has around 300+ books on it at the moment so I can read whatever I feel like it. Doesn’t help your syncing between different devices but I guess you could us Dropbox or something like that to link up your phone, tablet etc.