As far as the Pirates Online background information goes, the town in the fort is only accessible to Navy and EITC personnel.
However, there are many elements to Kingshead that seem to indicate that the fortress was not finished in time for the game's release. There are several passages that go nowhere and the mysterious back entrance. There is the warehouse that seems to serve no purpose either.
This, coupled with the unused jail in the main fort, would give one to think that maybe other things were intended but not completed, perhaps even stores and shops.
There probably is, however, since every player is a pirate, none of the stores at Kingshead would be available for pirates because if they are a Kingshead they are probably controlled by the EITC and Navy witch surely wouldn't allow pirates in their shops, thats my opinion. Hope this is helpful :)