That's an interesting dilemma. Without the iPhone, you can't open the backup. And you are correct, only apps and selected music/pictures/videos will sync over to iPad initially. Did you ever back your contacts up to your computer when you synced your iPhone. The options are to sync them with Yahoo, Google or Windows. If you did that, then you can sync your contacts back to iPad via iTunes. If you did not, you may be out of luck, unless you decide to buy another iPhone and set it up from your iPhone backup already in your iTunes backups.