Not really a full update, cause a bug got in my way.
I decide to wait till they recover. They might just be peasants, but every man (and woman) is a valuable asset (especially for building sites !). They all seem fine, if a little dazed, and a little heavily wounded.
After getting to the surface, I start cutting down some trees. Take that, nature ! This is for all that green stuff everywhere ! After gathering an important amount of logs, I notice that they're really weighting me down big time. This might be a problem for bringing them back to hell, as walking at a slug's pace leaves me quite vulnerable. Before going back, I fast travel to Dangerbreach and use the carpenter's workshop there to make a door.
I manage to make it back to hell and to find a nice spot on a hilltop without getting attacked by more demons. It's a miracle ! It's also far enough from the "fortress" so that I can build there. I put down all the materials and get to work.
I settle for a simplistic but easily upgradable design as a base for the conquering of hell. I decide to name the site "Hellfissure the Home of Conquerors". Sounds good.
Unfortunately, the building menu won't "detect" the logs and the door even though I dropped them on the floor right there, and it also deletes my plans everytime I go in and out of the building menu. It also doesn't save the name of the site. I don't really know what's wrong. It's probably an undiscovered bug, as I doubt someone ever tried to build something in hell in adventure mode before, and it's really annoying :/
If any of you know a way to fix this, please tell me (even if it involves dfhack or another external tool) !