Hi C.,
What a wonderful time for your daughter. Also for you to be able to share this with her. I lost my mother to heart failure when I was young and we didn't have much time together, so savor these moments only a mother and daughter can share.
Coming from the medical profession. I can tell you the best for her is ibuprophen for the cramps. It is swelling, and the ibuprophen takes the swelling down. She should only get it about every six hours however. Liquid would work faster for her. I would keep her active. I'm not sure what she is using either the pads or tampons, but my oldest daughter was using the pads until she was 13 or so. I didn't let her use the tampons because often times they can make the cramping worse in the beginning, just getting used to them.
I would also get as much literature from your doctor as possible. If you call your GYN they have literature for young women there, that you can have mailed to you, that will be directed to her. Perhaps you can read it and sift through it together. It's a confusing time for her and I'm sure it is a time when she is looking to you for all the answers.
Best of luck to both of you, she will be okay! With a great mom, how could she not!