you are getting a little confused. A property has a Blue Book which lists who is registered at that property. All Thai citizens must be registered in a Blue Book somewhere.
You will not be able to switch at Hua Hin Immigration but you will be able to use monthly 65k transfer after the first year once you have a full year of transfers.
yes thinking about it kinda difficult to finish a DTV until it has expired. You are correct the DTV can be converted to another type of visa at an Immigration Office but how easy that is for Chef's remains to be seen.
You can not work in Thailand on a DTV visa. However, there are plenty of foreign chef's working in Thailand so if you do get a job to legally work you would have to finish the DTV and then re-enter on another type of visa .