streaming/progressive download

Hello,
I need answers to these questions for research purposes to be used for a webpage i'm developing.

1. Can streaming software be installed on a normal web server and videos streamed on a local host?
2. Can streaming be provided over HTTP?
3. Does streaming software handle everything required to stream videos or do we have to do something as well?
4. If videos are to be provided using progressive download, can it be delivered using flash? If yes, how? Does it need to be converted first?
5. What does youtube use? I'm assuming progressive download, but how are videos converted to flash as soon as users upload them?
6. If progressive download stores videos locally, where exactly does it store them? Can users actually find them?

I hope i'd be able to receive answers to my questions.
Thank you.