Wishing you all the best in your Galciv3 undertaking. This Founders thing is an innovative idea: THEY pay YOU to architect your game and do QA for you. Evidently you saw all the overwhelming numbers of wish lists in Galciv2, and...well...supply and demand.... Lots of wish lists, not a lot of devs. It will be interesting to see how crowd-sourcing your game architecture (which is effectively what this is) works out.
I probably will not be joining as a Founder. This is already more-or-less my day job, and I don't want to come home only to do more. Also my feedback would be more low-level, such as in the project management side of things or in the coding--probably not where you want someone outside telling you how to do it. I wish I could, though--it would be exciting to architect your code so that third parties like me could "mod" it as if it was open-source--"mod" in quotes, because personally I would rather be contributing to the source code's trunk (or at least, close to it) rather than some unofficial mod. So I will just wish you all well, and I am pulling for you all. I hope Galciv3 goes well, and that you all have a good time doing it--in part because--as we know in the game world--the more fun you have doing it, the more fun the game will be.
p.s. about that pro-XML sentiment, I have to express my own, minority opinion here: I hate XML!! Whenever I hit situations where an XML configuration/extension makes sense, I always advocate some existing interpreted programming language (like Ruby) for your "XML". It's easier to parse (as in you just load the Ruby and boom, the data structures are all there). Plus the programming language automatically comes with all these additional capabilities for free, like include-file support, stored procedures, and dynamic data. And if your modders don't want to learn an entire programming language, simply give them templates for your "data" format (which happens to be in Ruby). Your expert users will just know how to do all the other cool stuff. I've done this before with success. White papers on it, the whole bit.