1) what caused you to leave the safety of your home and join the navy/bounty hunters? Money? Fame for killing equally famous pirates? Was your town ruled by a cruel pirate and caused you to hate all pirates? Come up with your own story!
2) what role would i fulfill on a ship? Navigator, shipwright, gunner, helmsman, cook, etc! Again be creative! You could also be an assassin hired by the government maybe. There is much conniving and backstabbing amongst the nobles.
3) what are your long term goals in the world? Do you want to rid the world of horrible pirates or maybe just protect the people who look up to you? Do you want to help bring a good face to a commonly viewed as corrupt government?
Aaand 4) what rank do you want to achieve in amongst the military? Do you want to be a leader of many or of few, and how will you do amongst your shipmates, (party members)