Many of the original links do not work anymore because of the change in the Internet. I do not know which Hatching Eggs link you meant but Hatching Eggs 101 by @Sally Sunshine has everything a person could want to know about the whole hatching experience from egg collection to actual hatching.Hi, the link to Hatching eggs is not working, is there another one? Is the sound the only way to distinguish males from females?
The guaranteed way to sex them is if it lays an egg, it is a hen. The "buckwheat" call is close to 100% accurate. Once they are mature, there are other ways to sex them such as a hen will look right at you while a cock will look at you from the side while he sidles around trying to decide how to react to you. During laying season, hens will have the feathers on the lower back area fluffed up higher than their wing feathers. This is often referred to having her bustle up. Once paired up, the cock will lay still in one area as his hen meanders about in a circle around him usually picking for feed. Cocks will often catch bugs and offer them his mate.
When his hen is on a nest, a cock will stand erect nearby watching for any perceived danger as his hen sits on the nest to lay an egg.