John: If you need to stream to many people, you'll want to get an MP3 streaming server (just like you have a web server for a web site). This can be purchase from many different places.

As for how many people your connection can support, please see the How Many Listeners? page of the Nicecast manual, under the Help menu.

This sort of thing is best asked to us directly via our support section. Please email us there if you have further questions.