1. it is measured by how many people live per square mile of an area.
2. One is the abundance of grocery stores and water to support a large or growing population of people. Another is the amount of schools or colleges to encore growing families to live near by. Third of all is access to public safety, such as reassurance from fire and police departments, and hospitals. Climate is one of the most important and what stores to have to accommodate the residents. Fifth would be tourism and how neat/ sanitary the location would have to look. Finally, good soil to grow crops.
3. (i’m not very sure about this one since i think you have to do that)
4. If we had more available resources and a healthier Earth, yes we would be able to live longer. However, factors like air pollution will affect the human population along with plants and animals.