Do any of you know:

1. What are some estimates as to the size of the universe?

2. What are some estimates about how many planets & moons are habitable by people?

3. What is the radius of the Earth?

4. To what depth in metres, and to what height, do humans live? I.e., we live from 20m below sea level in some places, to 3km above sea level in others? What's the range?