[ddouglass]

The Importedfiles.txt file tells Hoster what files were imported. So if you add more files to be imported to that folder then it will only show those files that need to be imported and not show the ones previously imported. Can you delete the file yes, but keep in mind that Hoster will no longer know which ones have been imported and will try to import them all over again.
Don't know about the foreign characters in the file names. This doesn't mean you can't use those in the stored Title or Artist name for the database as you import them, but you would have to correct them in the blocks before you import or in the edit after.