Decode below three cipher riddles:

26 L of the A
7 D of the W
1000 Y in a M

Why do people go to bed?

One night, a man runs away from home. He turns left and keeps running. After some time he turns left again and keeps running. Later, he turns left one more time and runs back home—but when he gets home, he finds a man in a mask. Who was the man in the mask?

What goes up but never comes down?

There’s a girl who has a large family. She has an equal amount of brothers and sisters, but each brother only has half as many brothers and sisters. What’s the correct amount of brothers and sisters?

There is something which is always coming but never arrives?

I have Rs.50 and I spend it in the way as below.

2 ladies and 2 girls need to cross a river in a boat big enough for 1 LADY or 2 girls. How do they do it?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

Here is a mathematical expression that also secretly tells a movie name. What movie is that?