Interesting ideas. I like how you summarized everything. I still think you should take a second look at that well-worn idea that bigger engines = better acceleration. Bigger ships would have much more massive internal support, and with inertial dampening to keep the crew alive, that can be extended to maintain the hull. It would add a very interesting dynamic to ship combat, and make people think through their strategies a little more. Small ships become flying eggs armed with shotguns. Delicate and slow, they have to wait until a ship gets close enough to blow it away. Also, starships are surprisingly delicate.
Bah. I highly recommend that you go out and buy some of David Weber's books. I suggest that you start with "On Basilisk Station." It's actually free online at this address:
Once there look up David Weber. Read any of the Honor Harrington books. Excellent military sci-fi.
Your paradigms for governmental types need a little tweaking. The problem with trying to classify something like that is that you have to either make lots of buckets, or a few massivly huge ones. Governments and cultures change over time, and in doing so can change their spot in your classifications. Britain was once a Rampant Expansionist style country, taking over large chunks of the world by force. Only after they had slowed their expansion and trade began to roll in did they move to a trading empire paradigm. Hitler had VERY clear reasons why he was invading other countries. Very few governments were ever reckless expanders, and those that were didn't last very long (i.e. Assyrians).
Also, your classifications tend to leave out the positive aspects for Warlike Expansion and Rampant expansion and the negative side-effects of Trade Empire and Peaceful.
Warlike Expansion: Brings a great deal of disunited land into the fold of one government that can oversee its growth and well-being. Much like Rome did when it tamed Europe. Those were very prosperous years under Roman rule.
Rampant Expansion: Can create the basis for a more stable government. China was a Rampant expansionist, primarily due to population pressures as well as the vast amounts of unclaimed land. Brings widely spread natural resources under one control.
Trade Empire: Exploitation of client states and lassiez-faire(sic) business policy can lead to tragic human rights violations and bring poverty, disease and oppression to those that toil underneath the business barons and government contractors. Think the pre-union work force in America in the early 1900's and during the Great Depression. Read "The Jungle" by Upton Sinclair to know what I'm talking about.
Peaceful: Pushovers that can leave their people undefended to the wolves that roam the wilderness. Like it or not, there will always be someone that is coveting your people and your resources, and it is up to you to defend them. A pacifistic ideal can only exist in a few circumstances, the most important being a very stable community of many governments together. Regardless, a country must be prepared to defend itself from threats. Reactive or proactive, it doesn't matter. As long as it is willing to defend what is rightfully theirs.
"That was quick."
"Well you know, when you don't do it right it doesn't take as long."