Another German here and yeah I also only had a single power outage (around 1h) in the last 5 or 6 years. Couldn't even imagine having no power once every day or even every week.
You don't need to especially not in your local network, but if you want to expose it to the internet then it would definitely make sense since you need a domain in order to use SSL encryption.
There are still people running Windows Servers? An Active Directory Domain Controller can easily be set up on Linux.
Yes I personally find it much quicker running a few commands via SSH and editing Docker compose files in a text editor than clicking around in some kind of web interface. It's also much easier asking for help or helping someone else I you can just send commands to execute instead of explaining different menus and buttons they need to go into.
I'll probably turn it off anyway when it pops up the first time.
That would be great
Yess the Jellyfin UI is so buggy, don't know why...