Walt's head is not frozen. He is cryogenically preserved. Yes, he is very cold but he is not merely "frozen". Every 18 months he is partially revived and his body is moved around. We don't really mess with the head since we don't want to mess things up neurologically speaking. I guess I'll back track a bit and say that metaphorically you could say his head is frozen in more ways than one!
Same answer as always...NO.............Cryogenics did not start until a year after he died. The whole body was cremated an the urn and ashes placed in the family stone.