Breeding lavender anything is very straight forward. If they are true ameraucanas they all should carry the blue egg gene so I wouldn't worry too much about that. If you breed Lavender x Lavender your going to get all lavender. If you breed Lavender x Black Split (a black bird that has a copy of the recessive lavender gene) your going to get 50/50 black splits and lavenders. Now my experience with lavenders is they sometimes have poor feather quality. This means that their feathers fray and break very easy. Crossing them back to black frequently is the best way to help this problem. Another thing that I found is that they sun bleach easily like a white bird. They will get a yellow tinge if not watched properly. Breeding Ameraucanas is very straight forward. Be sure your looking for a nice fanned out tail, when veiwed from the back makes a V shape. Nice full muffs, and correctly colored eyes. This is another important Lavender problem in my opinion. Nice tail carriage as well. Leg color shouldn't be a problem, and DONT worry about egg color at this point. I feel that type and color come first, then the egg color.
Tyler
edited to correct my terrible typing!