Speaking of the Deeps, and since no one has bothered you for information for a while, almighty Toad...
It's clear that the deeper you get, the more dangerous things become (as evidenced by repeated references to Balrogs in old posts, plus the giant frogs that leap out from under rocks and attack in some of the later movies.) I'm wondering, apart from the riverine cave, are there any other naturally occurring chambers deep in the mountain? These could have advantages (being basically free space the dwarves don't have to mine out, and perhaps more notably, don't have to haul all the rock away from) and disadvantages (swarming with terrors from below.)
Also, is there any provision for taking your dwarves out of the fortress to raid or destroy goblin/kobold/orc settlements? I'm given to understand from previous posts that successive games all transpire within the same world, so I was thinking it'd be pretty awesome to pay a visit to your previous fortresses once they're overrun by demons or goblins or what have you. Probably good for a little loot, too.
Finally, my own thought for a bloat -- books and libraries. (Probably inspired by recently playing Dungeon Keeper again.) Lots of options for creation -- papyrus (from reeds or similar plants), paper (from wood), or parchment (from animal skins) for writing surfaces, glue for binding (probably from bones), maybe some leather for a cover. Then you'll need ink, and quills. Why go to all the trouble? Well, I can think of lots of reasons. Bookkeepers and brokers might be less effective without ledgers to keep track of their dealings, laws could be recorded, there could be some proto-educational system for children or the unlearned, whereby skilled dwarves could write books on topics they know something about ("Fer on Carpentry") and others can pick up their skills.
The most interesting possibility might be histories... the system probably stores enough info already for a dwarf to write a good history of a fortress. "In 1021, in the reign of King So-and-So, Turråshemer didst establish a colony at Bèrnòrn. Their leader was Ghükghük..." -- you get the idea. These would probably be popular trade items, and might attract scholars (to learn) and scribes (to copy). Plus, if, say, the history of Bèrnòrn was traded to merchants, it might be preserved even if the fortress falls; later fortresses might be able to trade for the histories of earlier ones, heightening the sense of continuity.
But these are merely idle thoughts, so feel free to ignore them. You already have quite a bit on your plate, I can see...