I'd like a clearer definition of "fresh" as well.

I've noticed lately that when I buy ground beef, it's pink on the outside, but grey on the inside when I break it up to brown it. I'm definitely curious how that happens.

1. What factors affect the color of meat and poultry?

Myoglobin, a protein, is responsible for the majority of the red color. Myoglobin doesn't circulate in the blood but is fixed in the tissue cells and is purplish in color. When it is mixed with oxygen, it becomes oxymyoglobin and produces a bright red color. The remaining color comes from the hemoglobin which occurs mainly in the circulating blood, but a small amount can be found in the tissues after slaughter.

This is from the USDA site, more here