Basically, I use raw unsalted pumpkin seeds and buttermilk. You can also just feed them raw squash and pumpkin, but my girls won't eat it unless it's cooked. The seeds have curcurbit in them that paralyzes the worm and I can't remember what the buttermilk does unless it just hurries it through...
No, you cannot get worms from the eggs. If you see a worm IN an egg, the worm load in your birds is pretty horrendous and definitely time to worm them!
I didn't worm my flock till they were two years old. Really, there is no reason to worm them unless you think they have worms, especially if they freerange. Birds that range tend to eat plants that are natural wormers, if they're available. Mine are going on three years old and have only been...