once i am in the swamp i don't need the kiln anymore, Find a good swamp with surtlling spawners and bam, a coal farm with portals daisy chained in a loop. I once got luckey enough to chain 8 of those bad boys.

In regards to the wood, yeah no way to change the type, it would be like turning oranges into apples, Lead to Gold. That kinda stuff probably won't happen.

Just plant more regular trees or farm grey dwarves (got plenty of those after all)