Please, do not use a GUI, by default it will bind storage with -v parameter instead of --mount and in case if the disk would not mount for any reason, your node can be disqualified because of losing data.
Now this probability is reduced by adding a separate setup step, but it’s better to do not risk.
The identity should be placed in userspace, if it’s /public - then fine. This is related to how the QNAP is handled updates. I do not have a QNAP myself, but I believe that they removes all folders outside the userspace during upgrade.
Regarding OFFLINE issue, please, use this checklist:
To be able to access a web dashboard from your local network you can remove 127.0.0.1 address from the port mapping for the dashboard’s port, i.e. use -p 14002:14002 instead of -p 127.0.0.1:14002:14002 in your docker run command.
To change any parameter you should stop and remove the container and run it back with all your parameters include changed ones:
docker stop -t 300 storagenode
docker rm storagenode
docker run ....