Can you replace the question mark with the correct number?

What is the word or phrase below?
R | E | A | D

You see a mathematical expression in the picture. Can you think of a movie that this expression refers to?

There's a day, that comes around once a year.
To celebrate the man, you hold dear.
He gave you life, love and will pick you up if you fall.
When it comes to guys like him, He's the best of all.
Who is he?

People are waiting in line to board a 100-seat aeroplane. Steve is the first person in the line. He gets on the plane but suddenly can't remember what his seat number is, so he picks a seat at random. After that, each person who gets on the plane sits in their assigned seat if it's available, otherwise, they will choose an open seat at random to sit in. The flight is full and you are last in line. What is the probability that you get to sit in your assigned seat?

Imagine you are in a room with no windows or doors. How will you get out?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

We know that the number 7 is the prime followed by a cube. Which next number is also a prime followed by a cube?

Open a Laptop which is password protected. Hint for the password is given as below:

1 mobile 3 books 2 Boards 1 night 4 balls 2 lighters 1 ghost 1 hat 3 watches

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?