[thejeff]

Fair enough. I think most advice given here covers all three (10,15,20).
Nor do I see that the size changes the early strategy drastically here.
Distance between capitals likely only changes by a province or two for each step. That slows rushes, but only by a few turns.
Since early expansion tends to speed up quickly as everyone sends more expansion groups out, the large game only gives you a few more turns before indies are gobbled.

You may break out of the indy siege or recover from unrest and be ready to start growing again, but by that time there's going to be a lot less to grow into.

It may be recoverable in SP, but I've got my doubts in MP. Quit & start over is fine in SP, but it seems kind of obnoxious in MP. That's more of a problem with the way Luck/Misfortune works though, since it becomes less and less important throughout the game. If you survive the early game without a catastrophe you've essentially got free points. If you don't, Oh well, just start again.