I'll reply only on the second point because that's a topic I know (I happen to wander quite often in those quarries). And no, there is no mushroom production an

I'll reply only on the second point because that's a topic I know (I happen to wander quite often in those quarries). And no, there is no mushroom production anymore in the quarries. The paris area is too crowded now, and for economies of scale, existing quarries are too hard to use, and will use old quarries further away (but not as old as the "catacumbs" to have larger tunnels easier to work in). Also, what's often called the catacumbs are quarries dating back to the middle ages, and thus are narrow, turny, wet, etc. Just a pain to work in. Oh, and don't forget the dwellers that like to go down there, and would be sure to spoil all the crops.