From iTunes: Backing up, updating, and restoring your iPhone, iPad, or iPod touch software: http://support.apple.com/kb/HT1414
"If you upgrade or otherwise replace your device with a newer device, you may be able to restore the previous backup to the new device. You can upgrade one device with the backup from a different type of device; most settings will transfer to the new device.
Note: During the process of restoring your old backup to a new device, you may see the iTunes progress bar pause. If this occurs, please allow for additional time for the upgrade to complete."
See step 9 in the referenced restore instructions to see how to choose a previous backup.
This utility claims to be able to extract contacts & pictures from your iPhone's backup file. I haven't tried this, but the price (free) is right. http://www.iphonebackupextractor.com/