I wouldn't worry if you only sent your form back in the last couple of weeks and you haven't heard anything back, even if you said you could go for selection before christmas. Chances are they will have filled up the spots for the pre christmas selection before they got to your form, so you'll probably hear one way or the other after christmas.
I'm in the same position, sent back the questions by fax and haven't heard anything back yet. I also haven't sent anything but the answers to the questions, as when the email was sent that was all I was asked for.