Balance could be maintained by reducing the BR allowed in a port battle depending on the amount of ports your nation owns. I like the idea of a far-away King deciding policy and wars starting and stopping on their whims.
Do u mean the port bonuses? If so, they are 4 speed, 3 crew, 4 hull & 3 mast & rigging.
Ah, you mean upgrade slots. I honestly can't remember sorry, I'm gonna say 4.
Kia ora,
I docked my Purple Teak/Teak Trinc (Belize built) at Puerto Escondido at the last server shutdown. It seems to be missing from my docks when I logged in this morning. It had a Navy Hull refit & copper plating. I liked it.