You telling me you couldn't install nvidia drivers on Ubuntu? It's one of the friendlies distros for new users out there.
Official instructions: https://help.ubuntu.com/community/NvidiaDriversInstallation
TLDR: "sudo ubuntu-drivers install" if that fails read the instructions.
qBittorrent-nox is as separate as you can get. It can be run on the server without GUI. It also provides WebUI, that can be modified if you wish, but you don't have to use it. Moreover, most (if not all) settings can be edited through the text file and torrents added using CLI.
qBittorrent, when Web-UI is enabled (doesn't matter if it's nox or not), provides and API too. IF you have a client you can connect and manage everything using it. However, the only clients I know are for android.
You mean something like running qbittorrent-nox and connecting to it using web ui?
I have Thunderbird opened constantly, so I just open Google Messages in one of the tabs in it. Only problem is that it does not show any notifications, but I get them through KDE Connect.
I had the same issue this that site. I think it is caused by ad block. I browse the internet with Firefox that have ad blocking addons installed, but always have Chrome installed without any adddons to test sites just in case. And on chrome it worked OK.