Daughters from the Brown Leghorns, with a Cream Legbar father, can probably be added to your autosexing flock. They should have the correct genes, except that they haven't been selected for extra-obvious expression of the genes. So you might get a few more confusing in-the-middle chicks than...
Yes, they should look very much like Legbar hens, including the crest.
Yes, they should lay blue eggs, but I don't know what shade of blue (pale vs. darker.)
No pictures, but a few more details of expected chick traits.
With a Crested Cream Legbar father, all chicks should have white barring over the other colors on their feathers, and all chicks should have crests on their heads.
Yes sexlink, as you said. All chicks should have pea combs (like the...