i see. i took the 'not tv show' part a bit too literally. if your wanting orininal content the way to go is prob just wait for dark avatar and the customizable ai and see what sort of personality/style you can work into it and go from there. build up a collection of ai setting that work resonably well, then build up a story from there, rather than the other way around. let your mod grow organicaly as it were.
about shipbuilding. while i do like shipbuilding(alot) for many, if not most, mods it should be disabled. on some even research should as well. while it clearly does not take full advantage of the programmed resources it WOULD give the mods the appropriate character. using the full game for a, say Babylon5 mod, actually only gives you the visual flavor of the namesake. you don't have to play the Narn like Narn, you just do whatever you normally do but with Narn looking ships. if you are forced to use actual Narn ships on the other hand you have to be the best Narn you can be

. it's all too easy to fall back into old habits. putting the lockdown on shipbuilding, race customization, and tech takes that option away, making it almost a new game, even if a somewhat lesser one. the fixed ships would be useful more often than the fixed tech. for some mods it would make perfect sense to 'unlock' more advances ships by gaining tech. B5 is a prime example of that. they DID have tech trading and research over the course of the show. but a shadow 'doom ray'on a starfury, that's just...wrong. which is not to say that i disaprove of ppl using custom ships in the base game, far from it. but a mod, that's another matter entirly. on the bright side, it is the easiest thing it the world to have it both ways

if you've done the work to make a unrestricted mod it should only take moments to edit it to produce a restricted one, assuming Stardock included the option in the first place, of which i am uncertain. can you restrict research and shipbuilding in a mod?
for your pending mod tho this doesn't apply in the slightest. original content should use as much or as little of the game engine as your vision dictates.
oh god, i better get off my soapbox before i talk myself into a hell of alot of work, lol. your wanted the pot stirred? i think this should do it.