If you say my name, I will no longer exist. What am I?

A person was found dead on a big green land with no trees or buildings around. When the police arrived, they found a piece of rock lying next to him and the man was wearing clothes comprising of red, blue and yellow colours.

Can you tell who the person is and what was the cause of death?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

Known by all without exception, Forever here, for your protection, Sometimes strong, sometimes weak, Right after the night I come - hot and chic. And while millions of miles away, I always get to you, I find my way. No life around could do without me, Can you guess what I might be?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

Twice ten are six of us,

Six are but three of us,

Nine are but four of us;

What can we possibly be?

Would you know more of us?

Twelve are but six of us,

Five are but four, do you see?

What are we?

I know a nine-letter word having only one vowel.
Do you ?

I hide my treasure in the ground, my tail is big and fluffy. If you spot me in a tree, please don’t call me scruffy. What am I?