The earlobe thing is false. Earlobe colour doesn't have an impact on eggshell colour.
Regarding your Ameraucana, they would produce black and blue chicks, split for Lavender. Lavender requires two copies to express, one from each parent. Many breeders of blue and lavender choose to breed the colours separately and avoid the confusion that can come with blue, lavender and splash chicks hatching together; they can look very similar. As Lavender is a recessive, it can also hide in a line. I'm currently trying to breed it out of my BBS Araucana, without much success thus far.