As far as I understand it, the audition panel (of 2) is made up of heads of music from the consortium schools, however the head of music at St Clement Danes does not take part, so yes, they must just take the top ones that have listed them first. I think the system is quite fair, though, as the heads of music that do the judging do not know what schools the child in front of them has put.
If we had the academic test to do again, I would take my daughter out on the weekend before for some special treat that would have taken her mind off the test, as well as promise her one for when it was over. I also would have thought more carefully about how to get her to sleep enough during the week approaching the test. She was not sleeping well. She never said she was anxious about the test, but I think she was. I also wish now I had some individual sessions with a tutor to work on her exam technique, as she was too slow on the maths. None of the above may apply to you, hopefully, so just keep boosting her confidence in any way you can, I would say, and she'll be fine. (Nobody I know finished the VR paper, even the brainiest child in the school had one he couldn't manage.)