DE is diatomaceous earth---the little silica fossils of tiny sea creatures, and it is great to use for dusting the coop and run with---to dry it out some, but it is really not useful (as far as I can tell) for worming birds. If you do use it, get the food grade--it should say food codex on it. Food grade is a little more difficult to find, but the right thing to use. An alternative for drying is a product called Stall Dry. It is DE mixed with other additives. You probably want to use it in such a way that you do not inhale the product, either.
As far as worming your birds, I think that often Wazine (available at many farm stores) is the product to use for roundworm. It goes in the drinking water for a 24 hour period, followed by a water change. For two weeks following dosing, you will need to discard the eggs, and should not attempt to fix those eggs to feed the chickens or dogs, etc. as there will be pesticide in them. I have read that following up with a more broad spectrum product such as Ivermectin, is a good idea, but it gets a little confusing for me after that. I am not sure how long you toss eggs for, and if people really treat and toss eggs for a full month a couple of times a year or what. I have read most of what's on this site regarding worming, but there doesn't seem to be a definitive rule about length of time to discard. Good luck with your birds.