Well hell, as long as you're reading this I'm going to take the opportunity to further pick your brain. I'm still pretty new to the Kobolds (largest fort was about 80) so I'm largely operating on theory, but here's how I divide up my more military-oriented castes. Bear with me here:
Vipers are easy, they're given large daggers and, if they live long enough, seem to turn into wrestlers (knife-using isn't a military skill, right?). What effect does their bite have? I have trouble figuring out the effects of syndromes from the raw files.
Lizards are also easy, since they get such a wide range of weapon bonuses. I usually start them out with pointy sticks, since they're so easy to start making with bone/glass. Although as we've seen earlier, I've also considered using them as Bola throwers, since they get Throwing as a bonus.
Owls I haven't quite decided on: ideally they survive long enough to be teachers for new recruits; though I tend to put them all into a single squad for the same reasons I saw earlier in this thread: they can take the lead on taking down stuff in webs. They don't get any weapon bonuses, but I generally give them choppers.
Badgers and Turtles generally are given clubs, since it's pretty important to have someone dealing blunt damage.
So now, Kestrels: I agree that their stealth bonus is useful in gathering, and I generally have at least one Kestrel-Woodworker to make use of their bowyer bonus (I try to make the rest Coyotes). I don't make them Thieves, though, since that's a destination for extraneous signs, along with Masonry. I mean, how many Rats/Eels does one REALLY need?
The real question here, then, is whether or not a blowgun squad could ALSO be used as such a destination, since most 'Bolds will start with as at least Adequate, and blowguns aren't really used for their damage. The Kestrels' Gunnery bonus could be overlooked so as to have a squad with Bows or Slings, where they make use of their Archery bonus. Do they get a bonus using Bola Throwers; that is, do Bolas rely on both Archery and Throwing?
As I said before I am still a Kobold newbie, and I haven't really figured out their end-game. Case in point: I don't know how to use Witch(ers) or Druids. In fact I just now started a new fort that has a Witcher in it, and I'm wondering if I should start training him in the military, with what weapon, etc.; Same with Druids; do Druids need to be in a squad to transform, how should they be trained/equipped, do they only transform when they make contact with the enemy/do they do that beforehand, etc.
Hmm... oh and while we're at it, is there really any difference between Crystal/Clear/Green glass for the purposes of making weapons? Besides the Material Value, their values in the Raws appear to the same.