What has one letter and starts with an E?

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

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.

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

I make two people out of one. What am I?

Before Mount Everest was discovered, what was the highest mountain in the world?

What is the Surname of Barbie Doll?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?