I actually wanted to avoid too much C&C... i'm not a very good photographer myself and didn't want to end up sounding like slamming.
Incidentally I did a ballet shoot with my friend at fort canning on last Wednesday too, surprised to find 4-6 poses repeated in your shoots! Wonder if the ballet world is too limited in dance vocabulary =X
Anyway, I'll just comment on my thoughts for all the pictures k... take it with a pinch of salt, they're just my opinion.
1) bent leg. in back bend poses the arms should be behind the head, not covering. Motion blur also.
2) it may not be obvious, but I can tell you the front leg is not straight. both legs turned in, not sure if its intentional or dancers ability. I'd also like the right arm to be seen, perhaps in a straight line. (sort of like using the arm line of pic 3) Same in pic 6, right arm unseen.
3) I'd have her face the other corner (to the left) instead, because can't see the leg line of the back leg. take note of the fingers too. If you must, just give the dancer a 10 cent coin to pinch with the thumb and the middle bone of the 3rd finger. Thats the classically correct line. Or that's how we teach little children actually...
5) back leg... abit unclear if its to be bent or straight. but its pretty covered up so I kind of like this. Its harder to go wrong with Modern dance poses.
7) the hip alignment is 'twisted'. ie. its a major technical flaw in dance... covered by the dress and won't be obvious to non-dancers actually.
8) the bow +bent leg shows up here again, exactly like the first picture.
9) excellent position from the girl on the left, technically perfect. I just feel that they were off sync, the right girl is coming down already... if not I'd give you 5 stars for this shot!
Hm, to your question to hide the bow legs... its the nemesis of dancers to be born with bow-legs, training doesn't really affect, its genetics. How to hide it? Its through perfect turn-out, not an easy task either... usually you can only hide 1 leg, so you gotta play with the angles, the raised leg should be perfectly turned out.
Anyway its not easy, may seem like a lot of critics but your photos are commenable really. My friend and I shot 400 shots over 3.5 hours and only about 20 good pics... did a same jump over and over to get all the techniques in place.