I always recommend video if you can do it.
Be very selective and remember your purpose--don't bore them with lots of "cute"--but show her working on something she's passionate about. It's ideal if you can also include the work she was doing, too. (The paper, I mean.)
So, for example, film her doing some math problems that you give her, then include the page she "doodled" on. Try to let them see the way her mind works.
If you don't have video, audio recordings would work, too, but there the paper work is vital, and you might need to describe in writing what they're hearing.
Better to send too much than too little, I think, as long as you aren't going crazy with volumes of stuff. (Again, selectivity is important!) But I think I'd send more than what you've listed unless the poems and stories are really stunning and long.
Remember that your goal is not merely to demonstrate that she's GT, but to distinguish that she's HG+. That's a very different aim!
Best of luck! I hope she sails in!
