Such good questions.
There is a B&W diagram of exactly what the E-Locus looks like in chick down. Some non-wild types look a bit similar---and drat -- I cannot put my hands on the diagram right now right now. The author was studying downs.
The definite, clear, unbroken, dorsal stripe that is dark -- and forms a distinct - clear V on the female's forehead is one sign of e+. slightly broken, sometimes shows eb (brown) and completely broken is often eWh (wheaten) -- on the E-Locus -- Sorry I don't have it I will post when I encounter it. -- So starting with your chicks -- yes you should be able to tell the e+ (Wild type ) and select them for breeding. Of course that light head blotch on the boys will indicate a nice dose of B/B for the double factor barring gene. Autosexing has never been a difficulty with my hooligans -- they have other things that need work. :O) -- but I think that years ago when we did a survey and people selected Autosexing as the Number 1 trait of the CL that they were right on target........
Luckily for me -- I was able to attend a seminar that was presented by Grant Brereton who is the UK Plumage genetics expert, author of numbers of books on chicken breeding and chicken genetics, a Class A GBPC judge, and editor of Fancy Fowl magazine -- and a really great to meet and fun guy as well as someone with encyclopedic knowledge -- and one thing he told our session was that if a male has no black on his saddles -- then he is wheaten. -- so when I see a CL male with pure white saddles - I am suspicious of what may underly his E-Locus. Again -- it takes many many many years to have a lot of expertise, it is dimly possible that I could have mis-understood but it was kind of jaw dropping so I asked twice. If I had a male that had no black in the barring on his saddles (or no very distinct darkness contrasting the light -- but rather pure light )-- I wouldn't use him for breeding if I was having difficulty with autosexing.
And yes again -- the browns that turn blue eggs green will be difficult to eradicate -- (which is why I don't want any green influence in my flock -- ) --- by selecting and using blues -- you should be able to get to blue.
Those with insights and experience with these phenom. - please weigh in.