For the USB thumb drive, are you looking to use that for the backup destination, or are you trying to create bootable media to do a recovery?
As for the Backup no more often setting, if you are setting a scheduled job to run once daily, I do not worry about setting that. If you set your backup job to happen at a specific event like lock, logoff, or when backup target is connected then that setting comes into play. If you set it to backup no more often than 1 hour, then if you backup at 1 and lock your computer at 2:15 it would run another backup if you had that setting configured. It applies to the event based settings, not the daily.
Hope that clears it up!