Many things help determine breed.
Feather patterns, color, comb and wattle type and bird size etc. You may want to research sites like Hendersons breed chart to compare pictures of what you have and what they show. Keep in mind, hybrids are common and may vary indicators but a close guess will be fairly easy.
See: Related links
a common type of fowl is a rooster
If they have a comb
Bird
the colors are different.
you look at his spurs to see how old he is
Look at the related answers.
A Black Star rooster has a white dot on its head, where the females do not. Black Stars as sex-link chickens meaning you can tell their sex by their color once hatched.
No rooster can lay eggs.
They belong to white
Yes, because we have about 1,000 roosters but Galic Roosters are the rarest and I will tell you this if you promise not to tell, go on PornTube.com
Some type of disease or physical damage to the gonads.
at about 8 weeks old or so they start developing small differences. For example, their cones on the top of their head might be bigger, they might have longer tail feathers, and they might have a broader chest. They might be more aggressive, or even start to rooster when they are young. if they rooster, they are a rooster- and it is loud and might be obnoxious.