I only suggest webex it is my employers corporate standard and I can therefore host it at no charge; I think I can get access to Microsoft Livemeeting but I'd expect they would have similar Terms. 'd be happy to join another service is somebody somebody else has something similer.
Attendees of a webex session do not have to register with webex, it just asks for a name and and an email address (which are not checked and can be garbage) then installs the pluggin (which you can uninstall later).
wrt content material exchanged on the call I'd expect it to be shared on the basis of something like open source / creative commons license
http://en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_Attribution-ShareAlike_3.0_Unported_License