The Power Add-on Import allows the administrator to schedule your Import process from a remote file retrieval to provide more control over recurring imports from a full url where you CSV file resides and allows flexibility for scheduling the time for daily imports.
WordPress cron is not exact, it executes the next time a visitor comes to your site. WordPress times are UTC/GMT time NOT local time. Set to none and leave the URL blank to clear the cron job. Example: 14:25. (Default: empty = do not run daily cron)
Checking your server, PHP and MySQL to ensure the character set is correct will go a long way toward importing special characters like registration characters.