What do you call a toxic, hyperactive listening device?

I float to faraway lands carrying people and freight. I am filled with gas but don't deflate.

I cradle warmth in my gentle curve, a dancer in a porcelain sea, stirring tales from broth to brew, yet silent as I serve.

Red and small I burn if you fan me you see me grow before your eyes. I can be brushed away after the flames glow. I have no flame, but I still carry the burn. What am I?

What you do with the seat belts in your car. I'm also a way to tell someone that you're tying your shoelaces. In America, my first four letters are worth a dollar.