Answer:
I am something that floats. But after a period of time I fall.
It breathes fire in fairy-tales
Don't forget to do this before blowing out the candles.
Even the oldest ones can be described as current, but a little mainstream.
What is flat, usually square, and made from trees but isn't wood?
Before I grow I'm small. When I'm old I grow tall. When I die I give a mighty fall.