Hi Kevin,
I’m mostly familiar with the egg laying cycle of laying hens and not the first 18 weeks of the life a hen, which is called the Pullet stage.  If you want that info I would turn to someone in that business.
The rule of thumb for egg production is 1/4 lb of feed per hen, per day throughout her production cycle which lasts approximately 52- 54 weeks from the time she reaches maturity at 21-22 weeks old.  On average the average amount of eggs a hen will yield (lay) in a week is a little over 6.  
Eggs are graded for size using weight per egg grading class developed by the USDA.  Those classes run from Smalls to Large, Extra Large and Jumbo with smalls being the first eggs laid by a hen which then increase in size as the hen lays eggs throughout her production cycle until it stops when the hen is 70-72 weeks old.  The Large and Extra Large phase together create the longest part of the egg producing life of the hen.  When selling eggs in cartons whose label indicates  the size of eggs packed inside it, the weight of the dozen respective to that class must also be printed with it.  For instance, Large eggs must state that they are 24 oz, (1lb 8oz) 681g.
The composition of chicken feed is fairly standard and is composed primarily of corn and  soybean meal, with corn accounting for 60% and soybean meal accounting for 20%.  
The rest are other proteins or additives like vitamins.  This remaining 20% is usually proprietary information and is not shared with the general public because the producer feels it gives his or her eggs an enhanced appeal of taste, color or more efficient production.  Third party auditing systems like those with whom we contract ensure that this 20% meets organic and Cage Free expected standards i.e. that at a minimum the feed is free of antibiotics and that there are no synthetic additives. Organic eggs additionally require feed from grains grown without the use of Pesticides, Herbicides, Fungicides or synthetic fertilizers.  This is true even for Pasture Raised layers who actually are still dependent upon feed and not grass for their egg laying energy.
Hope this helps.
John Baker
Giving Nature