It is gonna be a while before the thing is anywhere near ready, for now I'm prototyping the hull. Then I've got to figure out the best way to attach everything (as far as I can tell, the hull and upper deck are both strung from the baloon frame, no solid attachments. this cannot be done in lego. I'm working on it though.
As for floating, I think it is well established that the ships in game would have some serious trouble irl. That said, if somebody makes one, I wanna see it. Actually.... I've got a friend with a 3d printer.. combine that with some model airplane engines..... hmm...