The second shot to me is by far the best. I don't care for the b&w conversion, but that's just me...I'm -very- selective about which shots I choose to desaturate. I think what would have put that second shot over the top would have been instead of books, some old sheet music/manuscript...ballet does after all generally go hand in hand with music. Perhaps the first few pages of Tchaikovsky's "Swan Lake" for example.
Here's a couple suggestions to maybe keep in mind if you go to shoot more...
Ballet being an art form is as such generally about "emotion" (much as is music, cinema, etc.). That's what you want to try and capture in the images. Now with most of these shots, I like the tattered look of the ballet shoes...I can easily imagine the bloodied up toes, sore/aching muscles that went with them and the hours and hours of practice to have earned them. I would personally try and put even more emphasis on this. Ballet is one of those arts where the artist makes it "look" easy but that is usually accomplished through a great many hours of suffering...literally.
I hate to sound cliche here but an image that comes to my mind is a semi-silhouette of a ballet dancer, sitting on a chair wearing the tutu with her legs out-stretched, with those same tattered ballet slippers, rubbing her calves... it brings a whole new dimension to "the agony of de feet"! 
I would also try to combine other elements that are emotionally associated with ballet. For example when I think of ballet (at least in regards to rehearsal, instruction, etc), aside from the tattered slippers, I also think of things like a fairly large room with one wall that's mirrored with a wooden rail running along it, a parlor grand piano off in the corner somewhere and perhaps a tutu or tights or even a simple set of leg warmers draped over the back of a chair. Later I think of the stage aspect of it...the setting, the footlights, the props, etc..
With that in mind since you said you "have never shot anything that didnt breathe before", I would also get either a teacher or a student involved...maybe shoot them in traditional costume (again such as a tutu or tights) in a few poses...the standing on one toe with one leg back, one arm straight up and the other arm wrapped around...just make sure you shoot while their actually dancing and don't expect them to hold this pose for too long! LOL!!! Some nice captures of a dancer in mid-jump either in a single spot light against a plane black background or even in a ballet studio against the afore mentioned mirror would also work. A dancer in the studio, with one leg up on that wooden rail doing those painful stretches that only dancers and contortionists can seem to manage would also work...hopefully you get the idea.
Ok...just a few thoughts for you. Good Luck!
Jim
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