My atiels laid 7 eggs and was wondering if someone could answer some questions?

I have been researching a lot from books and the internet but they don't always answer everything. For instance, my birds first laid an egg on the cage floor because I didn't have a nest box. I read that if you get it in a box right away that it may still hatch. I did do this. Also, two of the eggs had slight cracks and I covered them with light nail polish and a topcoat nail polish and let it dry. The birds DID NOT reject those eggs. Could they still hatch? I had read that advice in a book and on the internet. I think if I see another though, I'm just going to leave it because they get so upset and protective when I go in the box. Is it completely normal for them to try to attack you when you even try to change their food and water? I have been giving them their normal atiel mix of mostly seeds, Spray Millet (which they love), egg biscuits, cuttlebone, a fruit flavored mineral block with extra calcium!, and a special mix that is for nesting birds. Any advice? THANKS!