about the Harbour thing,
Drop the idea of a AI controlled Characters in there!
if you have Internet
make it a sort of 3D Multiplayer Lobby!
(for the ones that do not have internet will get AI characters interacting ofcourse)
1. if you use a mic you can talk to someone when they are close to you. so only people in a certain range can hear you talk.
2. you can check in a hall where you can check the status of certain players in the harbour (what boat they use, the amount of ships sunk and the amount of tonnage)
3. in the Bar's and stuff you can indeed go for a chit chat about ur patrol with other people
4. about 2, its actually a Profile thing you can update after each patrol and you can check it from others.
could be fun no?
edit: almost forgot for Career mode
LET THE CREW GROW BEARDS when your long on sea