Yeah, looks very zergy to me.
I dont quite know why you want to do creep... it only works if civ members walk barefoot on it, and I'd assume that they have some sort of clothing, even if it is called "chitinous plating" or something, because otherwise you get tantrums from "emberassed to be naked" thoughts. Even "creep covering" as clothing would work, with itemsyndrome it can get the speed bonus, and it degrades just like clothing, getting tattered and worn.
Dont know how feasable no diggin/no woodcutting is, because you have very little surface space, making hive/fortress design very difficult, and rather boring. In general I'd say that an underground hive would be very fitting, lore-wise... and of course they have access to vanilla DF buildings and reactions, no way to change that. But without access to the caverns and magma and candyland its quite a short game till you are maxed out.
I wouldnt make higher-tier units die after a while, I wouldnt like to play with it, but thats just personal preference.
And yes, I remember making units from this... I use it in MasterworkDF as well, look at the raws for "Broodmother". A drow pet, pop-ratio 1, gives birth to broodling, pop-ratio 100000, broodling has a secretion that affects itself with a transformation, transforms in the dwarven caste of slave, pop-ratio 1. They can do basic tasks, but they need to be a historical figure (killing something, making a masterwork or artefact) before you can make them nobles or put them in the military.
PS: Hundrets of throwaway drones causes tantruming. I made the kobolds in masterwork rely on throwaway military as well, and made them tantrum resistant. You can have a look at their personality values if you like. creature_kobold_camp.txt.
EDIT2: Oh, and have a look at the custom ZOMBIE creature in creature_masterwork.txt, it constantly emits stale blood. When they walk somewhere you have a bloodtrail following them... could be used for the creep... even if so many contaminants will hurt FPS afte a while.