Dr. A's displacement numbers make sense to me. The 15 mm would relate to total advancement of the chin point (pogonian). The 7mm CCW would refer to a posterior downgraft which, I guess for every mm of the down graft the BSSO to advance lower jaw will be able to advance the chin point by an equal amount. So, 7mm advance chin point with BSSO, 4mm extra it can be advanced via the maxilla advancement and 4 mm more via a genio which add up to 15mm overall to the chin point.
Your occusal plane does not appear too 'steep'. But it is of benefit to become less steep with the CCW-r because the Mandibular plane also becomes less steep with that. But the main benefit of the CCW-r Dr. A is proposing is that it will allow for a significant advancement to the lower jaw and the chin along with that. So, even IF you have bimax protrusion (which does not look like an exaggerated case of bimax protrusion to me) the proposed advancement is going to MASK it. The upshot of that is that you don't have to fret/worry about deciding to get an anterior segmental osteotomy.
You have an overly projected nose base. It is due to a prominent ANS (anterior nasal spine). Dr A has a technique where he can cut a 'V' shaped notch under the prominent ANS so the nose base does not get overly projected with the maxillary advancement. The ANS can also be trimmed down a little if the 'V' notching is not used. The bottom line of that is you don't have to worry about the chimp lip with the maxillary advancement because chimp lip is basically an aesthetic problem when the base of the nose is advanced, particularly when the ANS is ALREADY prominent. The upshot of that is the ANS can be altered in a way that can DE-PROJECT the nose base and avoid the chimp lip and allow the maxillary advancement to AVOID aesthetic problems that could happen when advancing out a nose base that is already projected out too far via the ANS such that it looks better on the face with relation to the bimax surgery.
As to braces (to move the teeth in which ever direction) or any other pre-surgical devices, that is a matter of the ORTHODONTIST working in tandum with Dr. A.
NOTES:
1: A detailed ceph analysis is done via high tech artificial intelligence programs that do them automatically by being able to find all the points to the bone structure and from there chart out the angles and planes. From there, Dr A incorporates the data to come up with a displacement proposal that corrects what ever deviations you have from optimized aesthetics. People on here don't do that for you. You don't include an actual displacement proposal from Dr. A; something where the a contour diagram of the profile changes proposed can be looked at that also comes with a chart of all the directional displacement vector breakdowns.
DISCLOSURE: The above statements relate to what Dr. A told you and my familiarity of his technique to avoid the chimp lip via being able to avoid problems that could arise from a prominent ANS. I can't speak of same/similar with the other doctors you will be consulting with.
