Answer:
I follow you all the time and copy your every move but you can't touch me or catch me. What am I?
Curtail me thrice I am a youth; behead me once a snake; complete I'm often used in truth when certain steps you'd take.
I'm a god a planet and a measurer of heat. Who am I?
You are my brother, but I am not your brother. Who am I?
What has a neck but no head?
I go in hard, come out soft. Blow me hard and I'll make a pop. What am I?