Multiple publishing pionts / text options for Interactive Server

The first important thing to understand is that FMS has nothing to do with your website. Any .swf on any html page can connect to any FMS application. The two are completely separate

As to your specific questions:

I have 5 websites all password protected for members, and I want all 5 members areas to be able to view my live video as I publish it. So can I embed the flash player on all 5 sites and have it pick up the same live feed.

Yes, but keep in mind that password protecting the HTML content does not protect the FMS application. If you need to protect the video stream itself, you'll need to employ some sort of user authentication on the FMS side.

Also was wondering if interactive server supports or has a chat box, so students can type questions as I am explaining things live.

That type of functionality is supported, but it isn't automatically available. You'll need to develop an application to support text chat. There is a prefabricated chat component available at http://www.adobe.com/support/flashmediaserver/downloads_updaters.html (look for the flash communication server authoring components), but it's really oudated... the communications components haven't been updated since 2003.

Can I stream my video from different computers or can I only use one ( the one I register it on ) I want other teachers to be able to use thier webcams from there homes and publish live videos as I do on my sites. ( At different times of course )

You can publish from any computer to an FMS application.