Recommend a look at the rtmp module for nginx https://github.com/arut/nginx-rtmp-module
On the issues.
1) is the address of the camera stream?
2) what is using your local ip? How do you represent? Or need local ip to publish the camera stream on the server? Then take ffmpeg and publish to rtmp nginx.
3) Yes, the camera stream is multiplied by the number of looking plus 8-10% on the transport Protocol. To avoid the only two options, if the local network - use multicast, but it still switches to configure need. If in the Internet, only a limit number of simultaneous connections, and look for the hosting that you will not be asked to go back ( many webhosts still have the footnote about broadcast media, please read the contract offer), or go on the same peg in some sort of datacert.