If you are considered a resident of NC then you would need to go by NC laws. If you still maintain a residence elsewhere and are considered a resident there…then I would assume you can go by that state’s laws.
In NC there is no such thing as “legal separation”. You begin your one year one day separation requirement for filing absolute divorce, the day that one of you no longer lives in the marital residence and you begin to live separate and apart. I’m not sure I understand the question about moving out of state. If your husband does is not moving he can prevent you from moving with the children if you are NC residents. If you both are intending to move to a different state, then NC law would only apply if you plan to file for divorce in NC. In which case, after you meet the residential requirement for another state you would not be considered a resident of NC and would not file in NC.