if I add a directory to the Library with d&d will files added to that directory be added to the Library in the future, or do I have to keep adding new files when I get them?
There isn't an option to monitor directories and automatically add new tracks. As mentioned above, you could just re-add the directory to the library (rather than individual files), but you don't need to bother with the "don't add duplicates" setting as there are never duplicates in the library anyway
