First, about the birthdate: She's not hiding her year of birth. Just the date. I don't know the reasons. It's all over the web that her birthday is November 30th, but it's not. She said so herself on one of the GoF press conferences. There's been some speculation that it might be October 3rd, but as long as she doesn't tell, we don't know.
She's 168 cm. It says so in her CV. That I can't seem to find right now, otherwise I'd give a link.