Have you tried tapping on the stalled downloads to see if they will "pause"? If they will pause, tap on them again to resume the download - but do that one song at a time, if you can do that.
If that doesn't work, try rebooting your iPad and see if that will allow the songs to start downloading again
Reboot the iPad by holding down on the sleep and home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider if it appears on the screen - let go of the buttons. Let the iPad start up.