I don’t think there’s any such feature.
If you don’t agree with the actions of a mod or admin, choose a different community or instance.
Use your client’s search function? On the standard web app, click the magnifying glass icon in the top right, pick the community, some keywords, and search.
No, that is not currently possible, but there is an issue open for it: https://github.com/LemmyNet/lemmy/issues/3057
You’re welcome to contribute to the project.
If you really want to be sure, create your own instance. Reddit could also up and disappear tomorrow. Less likely, since they’re trying to make it profitable, but Advance Publications could certainly say “no, we’re done, shut it down” and it would be gone.
I would suggest using the RSS feed an a reader that sends notifications.
Delete the directory, create the file. Docker creates a bind mount as a directory if it doesn’t exist.