Admin Custom Plugin List Files in admin Table

I'm building a plugin that works only in admin.

I've a page where I need a list of files, users can only download or delete the file.

I've this questions:

1. I don't know what is better to list the files in a specific folder or files saved in media library associated a specific category?
2. How can I get files list from a specific folder?
3. How can I get files list form a specific media library category?
4. How can I put and show the list in a WP admin list standard table?

Where can I find some code examples?

Regards.

Alex