Why give up the mole? That means it was a waste of mana. Obviously the GM is having no bookkeeping issues, so that's not really a reason for objection. You're worried about safe tunnels...I seriously doubt a five foot wide tunnel is going to end up collapsing the village in on itself. And being circular, it's going to be able to hold it's weight pretty well too.
I don't think our fortress should rely at all on mechanical power and transfer of power. Instead, plants and beasts man it. As some people had suggested, Gourd Trees would go well on it.
Plants are easier to feed, but there's a reason we don't see very fast plants...Plants are sturdy, and reliable, but they are very slow. Our bluemelons and bloodmelons can feed anything we want, so I see nothing wrong with making anything we need.
Don't stop mining. Mole is made for mining. Mole is already mining. And if we want a stable tunnel to the dwarves, ask the dwarves to dig it. That way, it lasts longer, has a smoother floor, and is engraved with pictures of cheese.
Ranger, how would mines damage an ecology? Because I'm pretty sure we're not going to have problems with ecology, considering we can easily expand. Fire allows us to clear out any forest or woods in our way, making room for new growth. We really, really, should have a custom ecosystem by now, where nothing is not our minion.