Breeding Zebra Finches?

I have a male and one female zebra finch. Now they have laid 2 eggs in the breeding box which I had attached from outside the cage. I have read somewhere that they can lay more than 7 eggs. Then what must be the reason behind laying just two eggs? The female finch sits on the eggs regularly. but will the 2 eggs hatch? I want at least one cute baby zebra finch. How many days will it take for the eggs to hatch?

What other than the seeds can I feed the mummy zebra finch. Please help me out of this.

By Arpita G