My bad, didn't understand dynamics. And wasted BO points.

Ship badges (to obtain a new ship, not upgrading class..just a new one) are due only on promotion? Or, turning question, I can someway change my cruiser to an escort?

You can go buy an Escort if you want, but it wont be 'free.'

Or you can just use the ship you have now until you get to the next Rank, then choose an Escort at that time.

Either way, the points arent necessarily wasted. You will eventually be able to use that skill. Just perhaps not until you get next Rank.