I have a Content Type A which can have Status 1 or 2. I then have Content Type B which is a child of Content Type A, which can have Status 1, 2, 3, or 4. Both A and B will be in the same list. Ideally, what I would like is to have Status be a list or site column with Choices 1 and 2, and then within B it gains Choices 3 and 4. But you can only declare FieldRefs within a Content Type, and that doesn't seem to let you add choices. Is my only choice to declare the Choices as 1,2,3, or 4 and limit access in A to only 1 and 2 on the form level? Or have them actually be different columns with the same Display Name?
When you inherit a content type you inherit the fields or rather the field references as they are. There is no editing of fields as you noticed there is only a reference towards a field. So if you edit the field than all fields that have a reference towards that field will change as well. The only thing that is somewhat flexible is when you add or remove field references you can decide to push the update towards all lists and libraries or not (specify true or false in the update method) but that's not the functionality you are looking for :-)