Well, that was just too easy. Wilfi returned to being unavailable later that night, even in safe mode. Don't know if an app is responsible for this. I'll wait and see if 5.1 corrects the grayed-out wifi before replacing the phone. At least the constant rebooting and icon issues are gone. Until I get updated, I'll look into Reverse Tethering my laptop to avoid being throttled on mobile data.