It's hard to tell from the light and distance, if you could get closer pictures it would help. However, those with the stripes (like a chipmunk) look like they are either Welsummers or Golden Salmon Maran chicks. If they have feathers on they're legs, they are probably Salmons, if not, then they're probably Welsummers. The yellow chick with the faint brown stripes all the way to the right looks like a Golden Salmon Maran. The stripes on it look too faint to be a Welsummer.
The first one looks like a Golden Salmon Maran, does it have feathers on it's legs? If not then it's probably a Welsummer. The second one looks like an Ameraucana, though to be sure I'd need a picture of it's face. The third could be either a Salmon or Welsummer. Both types are very similar as chicks, the main difference being whether the legs are feathered or not. If they have feathers on the legs, then they're Golden Salmon Marans, if not, then they're Welsummers. If they're Welsummers they can be sexed at birth.
I've actually never seen a chick like that. It's not an Ameraucana, the cheek down doesn't stick out enough. It may be a Sumatra, I've heard they can be solid black as chicks, though most of the time they have at least some white. Where did you get the eggs?
As for sexing Welsummers, you can tell by the triangle on their heads and their eye liner. Darker, more defined triangles and eye markings mean the chick is a female. Look at these pictures:
In both pictures, the female is on the left, the male is on the right.