Wanted to stop by and wish the Thrawn's Revenge team luck on their newest project. And I figure what's a better way to do that than to give some info that might be of some use to you?
http://soase.x90x.net/ - This site here has a bunch of tutorials on various stuff, such as modelling and rigging for Sins.
http://code.google.com/p/soaseplugin/wiki/RebellionSyntax - This site here explains much of the various code files in detail, listing what modifiers go where and such, looking at these pages alongside some code works quite well.
http://forums.sinsofasolarempire.com/407617 - A thread by modders, for modders. Has links to many resources, and is a place for modders to ask questions and get answers on various bugs they might not understand, and any other thing you can't solve with the pile of resources there.
http://forums.sinsofasolarempire.com/406367 - This is a planets mod for Sins. It was made for the explicit purpose of reflecting the Star Wars universe, and it has done a fairly good job in that aspect. The mod is fairly extensive in what it does, which is why it's mod in it's own right, versus being exclusively integrated into other mods. Might be of use to you.
Another thing I'd suggest doing, perhaps not now but later on, is to split off your various races into stackable mini-mods. You see, with how Sins is done, you can have multiple mods activated at the same time. This allows for a lot of flexibility, particularly when it comes to races/factions, as one can construct them, but have them separate from the core of the mod, which means that if this race is not being used in a match by player X, he can choose not to load it which will thus decrease the mod's overall RAM usage.
In addition, one doesn't have to remove all of a faction's ships/modules/etc in order for this to be effective; one can easily leave 3+ ships in the core of the mod (it's entity, mesh, and texture files), so they can be used in militias for example, while splintering off the rest of the faction's assets. Of course, this means people will have to confirm which order they plan to stack their mods in/what races they will use before playing a game, but this isn't much of an issue, from my experience.
That being said, I have good deal of experience with modding both EaW and Sins, and I'd be happy to answer questions for you guys if you have any.