This actually sounds amazing! This will probably balance it pretty well..
However once a Guild(?) is strong it keeps growing exponentially, how do you think other smaller guilds can counter that? there economy will be worthless pretty fast
I am also pretty sure most people want to play britain, but i cant agree with your statement britain or pirates
If other nationalities are interesting enough then people will certainly choose for those, i would love to play as a dutch merchantman!(yes i am dutch )
ps. sorry for my bad english