Eight of us go fourth, not back, to protect our king from an attack. What are we?

I am first found in caves, now prolific online; I am a depiction, a drawing, a symbol, or sign. I will convey whichever mood you could wish; or for that matter, a fist, flask, or fish. What am I?

Ten coins have been arranged as you can see in the given picture. In this arrangement, a triangle is formed pointing upwards. You have to invert the position of the triangle and make it point downwards while changing the position of 3 coins only. Can you do it?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

John was writing his first book. After saving the document, he locked his laptop with a password and mentioned some phrases for the hint box.

A friend of his tried opening his laptop but found out that it was password protected. Following is the hint that appeared.
1 mobile 3 books 2 roars 1 night 4 balls 2 lighters 1 ghost 1 hat 3 watches.

Can you help him in cracking the password?

Find the missing letter in the last circle logically in the given below picture.

I cry without having a voice.
I fly without having wings.
I bite without having teeth.
I whisper without a mouth.

Who am I?

What is the word or phrase?

Next Number in the Series,

5, 16, 49, 104, ?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?