How exactly do you go about making a functional fortress in this mod? All the stone I can find is that annoying surface rock, and I need stone to make a metalsmith's forge and lots of other things.
I chose a location where there were lots of trees and a few layers of clay and sand before meeting hard rock. On the level where you meet rock, designate a bunch of up/down stairs to see what kind of rock is below you, after that it's just digging out the veins in hopes of finding more veins and perhaps even magma. In order to use raw iron or zinc, you have to activate it in the stone menu though.
I went to that location without any sort of clay or rock material however, I survived simply due to the fact that I dug a trench and isolated a large area to sustain the people inside with enough wood to last for the first few fights.
Also, use the burners and sawmills to your advantage. At the sawmill, you can turn a log into 4 planks(blocks), at the burner you burn these four blocks into 8 pieces of charcoal. From one piece of wood, you can recover 8 pieces of glass or bricks of building material. This is going to be very important, seeing as how underground digging is going to be severely limited you're probably going to build a lot of the stuff above ground.
Edit: Found out more stuff that the enchanted will take offence in a trade. Not only do they not like food made from animals and wood, they also don't like weapons as well, but ammunition is perfectly fine!