but civilization placement and development is directly affected by biomes, so the same civ/history seed will not result in the same dispersement of sites and populations when coupled with a different terrain seed.
In that case, we'll just have to gather up the seeds one by one, starting with the terrain vote.
If you want kobolds to be able to mine, you're going to have to mod picks to be single-grasp at kobold size. I doubt it would have much of an impact on anyone else.
Assuming elves are to remain a stone-free society, they'll need to be able to make wooden mechanisms for traps. Give them the ability to make highwood as well, it's sufficiently elfy and it would make a much better arrow material than featherwood. Not to mention it's brown, unlike featherwood. Considered the idea of allowing them to make one wood type of every color, but that doesn't mesh with their above-groundedness.
Going to need to make the exotic pets tameable in Elf Mode (well, all modes, but especially Elf), because elves just aren't elves without war animals.
Civ leader deaths will be a much bigger problem with goblin players, since the dwarves will be sieging with their generals and etcetera (and we sure don't want those guys dying). In those cases, I recommend the player just forbid all entrances until they leave, or catch the leader in a cage trap and set 'im free.