What has no start, end, or centre?

A woman is sitting in her hotel room and hears a knock at the door. She opens the door to see a man whom she’s never met before. He says, “I’m sorry, I have made a mistake, I thought this was my room.” He then goes down the corridor and into the elevator. The woman goes back into her room and calls security. What made the woman so suspicious of the man?

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

Can you spot the man between the coffee bean in the picture below ?

Name a key which is hardest to turn.

There was an aeroplane crash, every single person died, but two people survived. How is this possible?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

Can you write down eight eights so that they add up to one thousand?

How many people must be gathered together in a room, before you can be certain that there is a greater than 50/50 chance that at least two of them have the same birthday?

I never was there, I am always to be.
You have never ever seen me, not ever you will.
Yet I am the confidence of everyone.

Who Am I?