Considering how little difference there is between ships after a certain point (Ares and Medusa? Not really. Herc, Myrm, and Percy? Could just as easily make all that two ships. Zeus? Once again, please), six should be plenty. Take the standard range of properties- speed, maneuverability, weapon compatibility, power, and toughness. Now divide by six- that's a decent difference. Give one or two odd properties, like high speed but no maneuverability, and you're set.
Yeah, the texes look vaguely cel-shaded. The interface looks much like every space sim's I've ever seen, and pretty much like most flight sims, too.