Try to read discussions on iTunes store forum, will get better grasp of the problem. In short when you purchase something or get something for free from iTunes, your apple id is embedded in purchase. The fact that you decided that you have different e-mail, is unknown to those apps or music. If you want to stay with new one, you d have to repurchase stuff or go to old one.
All apps are forever tied to the Apple ID (often the case is your e-mail address) used during purchase.
If you want to change the email address associated with the Apple ID