Can I back up my music from a iPhone 3GS to a iPad?
Can I backup my iPhone 3GS to an iPad just by pulling up my apple id?
iPhone 3GS, iOS 5.1.1, Backup from iCloud
Welcome to the Apple community.
Essentially, the answer to your question is no. You can re-download music that you had purchased through the iTunes Store, however if you can do that on the phone itself. So there is no need to do it on the iPad as a backup.