Hopefully she would never start laying eggs, a lot of hens don't. If she did, but was fed a well balanced diet (and the one you posted there sounds very good to me), she would be at very low risk for it. This page explains very well what to do if your hen lays eggs and how to get her to stop. You are supposed to leave them in because if you take them out before she loses interest, she will lay more to replace them. Anyway this page explains very well the steps to take for it should the hen start laying.

http://www.cockatielcottage.net/questions.html

I really didn't experience a "puberty" stage but I never raised a male from a chick before. There is real difference between the different colors in tiels, they are all the same species, just different colors the same as, for example, yellow labs and black labs.

Please don't apologize for your questions, I think it's great you are researching and questioning before getting a tiel, so that you are prepared to deal with anything and everything that is involved