Answer:
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.
If you have me you want to share me. If you share me you don't have me. What am I?
I am always running but I never get tired or hot. What am I?
The 8 of us go forth and not back to protect our king from a foe's attack. What am I?
What loses its head in the morning but gets it back at night?
When is it bad luck to see a black cat?