Im gonna drop a bit of a mutation bomb on you with midori. To me midori looks like a Dominant pied opaline spangle light green cock. Green is easy to see, dominant pied is clearly evident as well, but makes the other two mutations harder to spot as the pied gene has removed most of his wing markings. His lack of head, neck and shoulder markings definately indicates either spangle or opaline - you can spy out the spangle because of yellow/white tail and the white cheek markings. I say opaline because from what little wing markings he has, they appear to have his green body colour in them. Could you confirm this or put up a clearer shot of his back?
I would love to see the hen just to confirm her exact mutation but i'll put up some rough expectations based on what you've told me.
If he is a Dominant pied opaline spangle green bred with a normal green hen you can expect:
100% opaline females (opalines will be easy to spot, because normal babies have grey down feathers, opalines have very very white down feathers), 100% males split for opaline.
50% chance of any chick being dominant pied
50% chance of any chick being spangle
25% chance of a chick being both dom pied and spangle (50% x 50% = 25%)
25% chance of a chick having neither!
You could roughly work it out and say you have a 12.5% chance of getting an opaline dominant pied spangle female (50% chance of a chick being female x 50% chance dom pied x 50% chance spangle = 12.5%, or roughly 1 in 10 chicks).
Of course if he is not opaline, then expect dominant pieds, spangles, and normals
Also, the older chick is grey because the down feathers have come through and now the darker body feathers are starting to form and break through. They have much more colour so are darker, and the other chick will look the same once it is that age.