Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

Pronounced as 1 letter, And written with 3, 2 letters there are, and 2 only in me. I’m double, I’m single, I’m black blue and grey, I’m read from both ends, and the same either way. What am I?

What is red and smells like blue paint?

How can one talk without saying a single word?

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?

There is a barrel with no lid and some wine in it. 'This barrel of wine is more than half full,' said Curly. 'No it's not,' says Mo. 'It's less than half full.' Without any measuring implements and without removing any wine from the barrel, how can they easily determine who is correct?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

A man is found dead in his bathroom naked with blood scattered all around him. The bathroom was locked from the inside and there is no trace of any struggle. There is nothing in the bathroom except his pant with the belt still around and his shirt. Also, the medic team can't find any incision in his body that may have been the reason behind so much blood loss.

The Police department is clueless regarding this murder mystery.
Can you?

A man embarked on a questionnaire game. He kept asking the same question to whomever he found. The answer each time was different.

Can you guess what the question was?

Most people think of me as money. But when they find me in the water, they won’t get any money out of me. What am I?