Does Anyone Understand Xbox Rewards?

I am so confused with this Xbox Rewards program . I am thinking of getting the Destiny Download but trying to figuring out the reward program is almost impossible.I looked threw the FAQ , Left Question in their Forums and I still have no answer.I think they left the details Vague on purpose. I do have it preordered from gamestop but I was figuring I like the digital games they are always right their and if I can get a little rebate that would be a plus.I think I need a Lawyer to look of the Xbox reward rules.