I'm OK with a larger earth like planet. As I was designing the land masses (even at double the distances) I had found that over the course of 2,000 years (roughly) my cultures would become a lot more intermingled than I had originally anticipated. I don't mind that, but I want a majority of it to happen in story or game. With more land there's more elbow room, and "we got ta got ta git cha some elbow room," to quote Schoolhouse Rocks.
I'm still looking over the vast amount of information you provided. Will post tonight.
One question, when the wind patterns reverse themselves from winter to summer and back again (if I am understanding this correctly) I am sure they don't just wave at each other and start running back the way they came, right? Is there a gentle transition?