Specific nutritional specs questions

What exactly makes a pellet a good quality for a chin? What makes it a bad pellet for them? (Other then the basic no extras, fruit, veggies, seed, nut etc) What key nutrients are needed and what percentages are required? What can make a specific rabbit food safe for chins, but others not.
That whole kinda thing...

and

How about the hay? What are the nutritional requirments from hay? What is the nutritional difference between the hays (and non nutritional)?