Why do we need theatre?

My name is Renee, and I am studying Drama as part of the HSC. For my individual project in this subject, I will be doing a research report, which will focus on the research of theatre itself, and on the question "Why do we need theatre?"I was wondering anyone would be interested in answering some questions, as I am looking at gaining a broad perspective, from a range of people, in a range of fields. These questions would include:
What is theatre?

What is it's purpose?

What do we value about theatre?

How is it affected by film and TV?

Is Film and TV a form of theatre? Why or why not?

Is sport theatre? How does this effect live theatre?

How is theatre surviving in the 21st Century?

How do you get more people to see it?

If there is anyone out there who'd be interested in answering these questions, I'd really appreciate it!!

Thanks!

P.S. You can be completley honest - I'd really like to know what you think!