If your tethering option has disappeared then all you need to do is go to the Settings>General>Reset option and Reset Network Settings should cause your phone to reset and the option to reappear.
The greyed out ipcc file is an issue with the version of itunes you are running. You will need to run beta 5 for OSX to have the option for updating the carrier file.
Good luck everyone
The greyed out ipcc file is an issue with the version of itunes you are running. You will need to run beta 5 for OSX to have the option for updating the carrier file.
Good luck everyone