Those are both things that a window manager doesnt really do. I havent used i3 much but ill try to point you in the right directions.
For caffeine, depending on your bar, i believe most of them have modules for that.
Then for locking/shutting down, you’d want to look at i3lock, xautolock, xidlehook, and probably many others. Can’t guide you to the right commands, but this forum thread seems to have a lot of the info you’re looking for: bbs.archlinux.org/viewtopic.php?id=208699
Apart from all this, ive learned the most from a mix of looking at other people’s configurations and reading source code. The documentation is super messy, especially if you want to make use of flakes (which i personally recommend from the get go).
People run their stuff in docker cause it tends to make the process more straight forward.
The question is specifically about isolating your torrent client to a VPN only network, that way leaks are impossible since if the VPN goes down, there are no other networks accessible to the container.
Hm ok im not familiar with the 13. Tweaks on the 12 (and i think the 13 too) are needed only for the brightness keys.
Personally i would try a reinstall, as unfortunate as that sounds. Especially since it sounds like its a pretty fresh install.