Right, and completely agreed with that, but I think that SimpleX is just better in most cases (not on battery life for now), as it could be also self hosted
If you are just torrenting and using it for downloading some stuff and nothing more, use the cheapest as NordVPN or Cyber ghost these are good for this, BUT NOT FROM A PRIVACY POINT OF VIEW
You can download a lot of music, very safely without anything. But maybe it could depend of your country. But if it's a "okay" piracy country you shouldn't any issues, even when sharing I've seen a lot of residential IPs
Seen a lot of different opinion in this, but personnaly I would recommended this.
SimpleX, for the most privacy (but not really appropriate here)
Wouldn't use any of threema wire and else, as it's not the best.
A good option in the case of this project is a matrix server, if the group is public it's the best thing. Try to host it somewhere else than matrix.org.
Will have no real hiding but surely anonymously if done correctly
It can run as long as your on the same network as the other instance and for the chat export in readable format, I actually don't know, sorry