With the help clues provided in the image, can you find the 5 digit key?

Krish is 45 years old and his mother Crishtina is 73 years old.

Can you find out how many years ago, his mother was three times his age?

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

Two brothers were watching a horror film on video late one night. One brother dozed off and dreamed that he was being chased by the crazy man from the movie, who was trying to kill him. In the dream, he hid in a cupboard. There was no sound except his heart pounding, and he had no idea where his crazed captor was. He was terrified! At that moment, the video finished, and his brother put his hand on the shoulder of his sleeping sibling to wake him. The shock at that tense moment was enough that the sleeping brother suffered a massive heart attack and died instantly. True or false?

What's the only room from which no one can enter or leave

Can you replace the question mark with the correct letter?

6 + 6 + 6 = N
7 + 7 + 7 = E
8 + 8 + 8 = R
0 + 0 + 0 = ?

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?

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

What occurs twice in a week, once in a year but never in a day?

I have an eye but still cannot see.

Who am I?