You could give madsonic a try (http://www.madsonic.org/). It does everything you want, and you have to have a user account to log in, so you would be in control of who has access to the box. You can view which users are using the most bandwidth, and stuff like that. I have a script to install it pretty easily if you want it.
"Madsonic instantly transports your media to any HTTP connected device regardless of bitrate. You can stream to multiple players simultaneously. Madsonic is designed to handle very large music and video collections. By using transcoder plug-ins, Madsonic supports on-the-fly conversion and streaming of virtually any audio and video format, including MP3, OGG, WMA, FLAC, APE, mkv, mp4, and more.
Yes and yes. I've actually just uploaded those two to 4shared.
The Empire Strikes Back: http://www.4shared.com/video/wrqPas9jce/TheEmpireStrikesBackDespeciali.html
Return of the Jedi: http://www.4shared.com/video/bhrswtxFba/Return_of_the_Jedi.html