With Araucana based blue egg layers, the blue egg shell gene is closely linked to the pea comb. This will not work with Cream Legbar based blue egg layers though.Crossing a blue layer (as long as it has 2 blue genes) with a brown layer should yield green eggs as the chick will get 1 blue from one parent, 1 brown from the other. If the blue layer has only one blue gene your odds of getting a green layer drop to 50%. The OE hen has already reduced your odds to 50% since she has only 1 blue gene.
Leg color has no bearing on egg color.
Brown Genes are a lot more complicated. There are 9-13 of them and there is also a dominant white from leghorns.