This part is probably no longer true. For example, there are now 055 destroyers named after Lhasa, Zunyi, Yan'an. These are not the first choices for the average members of PLAN once they complete their services.
??? since when average sailor has a say on which ship he/she can serve, in any navy? You are assigned to a ship, not the otherway around.
The only thing you can do is ask, something like, I hope I could get somewhere close to my hometown, or I have certain skills that could be useful in someway and the recruiter may consider if the circumstance allows
I think this is more related to the "rankings" of HK, and Macao, too. The chief of these two SARs, after their tenures, have the chance to become a vice chair of the Political Consultative Conference (政协副主席). Average provincial governors do not have this kind of opportunity after their terms. I would consider HK and Macao on the same level as Beijing and Shanghai in political significance.
Just letting you know, vice chair of the Political Consultative Conference is more like a symbolic or ceremonial role, in this role you are going to have high status , some influence but absoulutely no power, and more importantly your path in Chinese political system is concluded. On the other hand, near half govenors can enter political bureau soon or later......
HK and Macao is not in the Chinese city tier list so there is no direct comparision between them and other capital cities like Beijing or Shanghai