Need an answer to a riddle

One's image in a mirror.

Riddle: It's 7:00 AM. You are asleep and there is a sudden knock on the door. Behind the door are your parents who came to have breakfast. In your fridge are bread, milk (pasteurised), juice, and a jar of jam. To answer, what will you open first?

I'm not clothes, but I cover your body. The more I'm used, the thinner I grow. What am I?

Brothers and sisters I have none but that boys father is my fathers son?

On hot summer days, sit under my square of shade to keep the sun away. A landmark at a park or a popular setting for a wedding. Little pillared tin roof, no doors, focus your gaze on the outdoor galore.