2 and 4 are good and reasonable reasons. A good boss has one responsibility to make the team remember happy and has good personal growth. If your boss know your thoughts and there is such opportunity available, s/he will consider you first with the assumption that you are a good fit.
Another possibility is that you need to pay attention to job openings in the head quarter, if there is one you like, why not apply for that?
Another possibility is that you need to pay attention to job openings in the head quarter, if there is one you like, why not apply for that?