

Generally, Linux Servers are best administered from a command line. At least in the beginning to set everything up. In turn they are faster on lower hardware as they dont even have a graphical desktop at all so need less resources. You could of course install a windows server OS. They can be fully administered through Remote Desktop and a GUI.
There are multiple projects to make self hosting more accessible (like casaOS). They automate many steps of the setup and then offer you a webUI for further steps. Maybe have a look here https://github.com/awesome-selfhosted/awesome-selfhosted?tab=readme-ov-file#self-hosting-solutions
Decryption is not related to root permission.
If the ENCRYPTED drive is mounted to the container, then the container can decrypt it.
If the DECRYPTED drive is mounted to the container, then the container never knows it was encrypted in the first place.
Second case is easier BTW. Just mount the drive on your host, type in the encryption password and you get a new, unencrypted drive. Specify this new drive in your docker compose/docker file.