What brings you down but never up?

Can you calculate the probability of getting a sum of six when a dice is thrown twice?

A boy was driving a car, a girl took a lift from her. She asked his name. The boy said - my name is hidden in my car’s number, find it if you can. After this, she got down Car number was [ WV733N ] Can you guess the name now?

I am eight letters long - "12345678"
My 1234 is an atmospheric condition.
My 34567 supports a plant.
My 4567 is too appropriate.
My 45 is a friendly thank-you.
My 678 is a man's name.

What word am I?

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

Count the squares in the matchstick puzzle below?

Without looking at a calendar, within a minute name, a boy's name using 5 consecutive 1st letters of 5 consecutive months

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

I never was there, I am always to be.
You have never ever seen me, not ever you will.
Yet I am the confidence of everyone.

Who Am I?

What is the end of everything?