Ultimate Strategies Mod is a good place to get formations (and strategies) from. It is a compilation of all that I could find.
FQM seems to have a few fans here and there. Might be a decent place to get quadrant, system, etc. data from. I'd recommend using the "no ast" type quadrant options, to avoid the excesses created by the full asteroid rings typical of the mod. You would have to modify the non-mid-life quadrants to use the no ast type, but that's just a matter of copy/pasting the respective system lists from the mid-life no asts.
"text file additions - design types, cultures, etc."
There are some decent base files for the flavor files (empire names, design types, etc.) included in FQM as well. I think they are in both standard and deluxe, but I forget. Might be a good base for your purposes.