Thanks for your feedback guys! I've already been experimanting with some GIMPressionism to have that chalky style going, but nothing good yet. And as you were saying, it's better to worry about it once the maps are in place. Speaking of wich, I'm now and then hand-drawing sketches of the eight level for the main complex. Only one of them made it into the digital world yet, I barely can get the time to work on the maps these weeks.
The misinformation is in the nature of these maps: they are supposed to be drawn from memory by the dwarven group member. And he's not been at this place for a few decades. Instead, orcs and goblins and the like fester the once mighty stronghold, which means I totally intend to have a second set of maps with red labels like "big bad guys here".
Hopefully this weekend I can spend an hour or two with my GIMP. When the first four levels are complete I will post them right away. Until then, cheerio!