What word begins and ends with an E, but has only one letter?

You can find some missing letters in the picture. By placing two particular letters in the spaces, you can form a nine lettered word beginning from one of the corners and going clockwise direction to the middle. Can you find out the letters and the word?

If eleven plus two equals one, what does nine plus five equal?

John’s parents have three sons: Snap, Crackle, and what’s the name of the third son?

What has many keys but can’t open a single lock?

A man and a dog were going down the street. The man rode, yet walked. What was the dog’s name?

Give it food and it will live; give it water and it will die.

I am a type of food that is often found in the fridge and can be white in colour. What I am?
Hint 1: I am a dairy product.
Hint 2: You can spread me on the bread.

One day, John and his friends were playing around. Jacob hit something with a Pin and it popped. John's dad came into the room that very moment, but he wasn't mad. In fact, he was smiling. What did Jacob hit?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?