First feis- advice and help?

I am going to my first feis this week and I'm really confused. I am a beginner but because I am too old, I have been entered in Primary instead. So... do they count you in before you dance? Also, once you have finished dancing do you bow to the judge, then go back in line, then bow to the musician? Plus I think I am supposed to wear a polo top and pleated skirt and just have my hair in a pony tail, is this correct? Also, any other tips would be REALLY appreciated.