Question of Firefox. For Development team

Hello.
I am a student at univarcity at Japan.
I belong a Computer Science major. We are doing a project about Global
Collaboration.

I am sorry to bother you, but I was wondering if you could answer a
few of my questions about Mozilla firefox.
This would be a huge help to me and my class.

   1. There are various functions in Firefox, but, for the
development, does adopt the opinion of us user?
   2. It is the Internet that became indispensable to our life, and
cannot miss the browser when I use the Internet. As for me, I think
that Many functions are pounding Firefox and It is easy to use the
neat design for a user very much. However, I think that the users
increase now in Japan, but think that there is the person whom I can
employ still more. Can there be something doing it to get many users?

   3. Why can you use it free?

I look forward to receiving your reply.

Yours sincerely