Answer:
I hide but my head is outside.
Thirty men and ladies two, gathered for a festive do; Dressed quite formal, black and white; soon movement turned to nasty fight.
Hard to catch, easy to hold. Can't be seen, unless it's cold.
The French word for 'fun size' in women's clothing.
I am always hungry, I must always be fed. The finger I lick will soon turn red.
You use it between your head and your toes, the more it works the thinner it grows.