I like tremblefist but agree the exploits you described should be prevented.

I personally feel that empire should not work with orcs ever, since they cannot be orderly.

I'm on the fence re plague. Maybe just make it so that he won't plague villager targets under level 30 or something. Those above that can just make sure they keep enough moves to make it back to the village, or alternative spots.

Or people could just play defenders more, instead of berserkers.