How do I know when I am getting close to the file size limit when I am working online? I'd there something I can do about it? I notice it keeps track of all my files, even the ones I am not still using within the game. I hope they don't count against file size if I am not still really using them. Otherwise, I think I am in trouble.

There is a help page about this:
https://docs.textadventures.co.uk/quest/publishing.html

By default, Quest will indeed include any files you have added, but then deleted. You need to also delete the file itself from the game folder (Quest will put a copy there if you added a file from somewhere else).

ETA: I am assuming the desktop (offline) editor. If you are using the web version, I am not sure you can delete the files.

Thank you for answering this post, however, I still don't know if I am going over. I had read the page in the link through already, and even the writer of that article had no idea, as to file size count when working online.
If anyone knows how I can delete unused files from the online cache, or knows that I don't need to, that would help.
I may, maybe, just copy everything to a folder and work offline, as soon as I am not confined to my phone.
😳☎️