My music files are stored on a NTFS HDD. And I have NTFS-3G access for read-writer. I've noticied that some tags are off (no surprise) so I edit the tags manually to fix them usually. But if I were to edit them in Amarok would they update the real mp3 file? Or would it only update the database that Amarok built?

Yes, the tags are written to the files.

The scores and moodbar data (if you have that installed) aren't