Choosing a different government type on the create game screen can also alter, starting RP, starting number of shipyards, starting number of reseach labs, starting number of installations, starting number of ground troops and the various attitude modifiers that are listed on the race details screen. There may be a few other effects as well, I can't recall if any effect economic/production efficiency.
Is there actually a documented list anywhere? Using SM mode, I can get a bit more visibility into the values that change, but I can't find any documentation on what the ratings (xenophobia, militancy etc) actually affect. I can kind of guess most of them, but some hard info would be useful
Your government type, together with your race, influences a few values, like xenophobia and determination, that will change how you can interact with other races. Unless you strictly RB, most of those values are only meaningful to NPRs or in direct diplomatic interaction with them.
On the "Create Game" screen, what does changing government type do besides altering your research and manufacturing capabilities? The tutorial seems to indicate that it does, but what exactly are the effects?