For the ones the say lower with (fraction), do you want me to remove, say, 1/3 of the cost when you say "Lower with 1/3" or set it as 1/3 the current amount?
As for the 1 per system ones - I can see how those buildings would become overpowered. I'm not sure about the barracks, Borg UB, or museums (perhaps the science boost becomes overpowered?), though.
Battleship - It's not actually part of the mod itself, just a remnant from Final Frontier that remains in until I get the late game units online. The same is true for squadrons.
Civics - not sure which techs to make for requirements of most of them
Withdrawal of units - not sure if your opinion on this matter here is affected by the battleship being in or not.
Max XP from barbarians - perhaps the rest of the community could comment? I'm happy to change it, though I would like to hear input from the community on this.