Yes, just copy metadata.db to make a backup.
The books are stored in folders with paths that are constructed from the author and book title, so it is NOT enough to just swap values. When you update authors or title for a book in calibre, the folder for that book is updated as well. That is why a plugin might be better, it would allow moving the books as well.
I think it would be better to update some custom column with suggested action. Perhaps several custom columns with suggested new values for title, author and series. Then that can be reviewed and updated in calibre.
It could also be possible to make a script that creates a list of actions like swap author/title, and then use the command line tool calibredb to execute those changes from the same script that finds the actions to perform.
http://manual.calibre-ebook.com/cli/calibredb.html