When does milk expire if it is frozen?

I recently heard on tv that a good way to save money is to buy milk on sale and freeze it. I inadvertantly froze milk before when I forgot it in the trunk of my car this winter; it was still white and tasted fine. However, a few weeks ago I decided to try this and I bought a gallon and stuck it in the freezer. It was the 1/2%. It turned slightly yellow as it froze and now I am ready to drink it and want to put it in the fridge to thaw it. Here's my issue: will it go back to turning white? Also, the expiration date was a week or two ago; since it has been frozen, do I have to drink it within a certain period of time? Or when I freeze milk, does it still have to be consumed before the expiration?