Hi,
Your internal users will not be able to have "full" functionality unless they are OCS-enabled. They can only join existing meetings that allow "anonymous" participants. They should, however, be able to share applications if you give them rights as "presenters" during the meeting.
You won't need to install a Web Conferencing Edge server unless you would like these users to attend LiveMeetings from outside your corporate network (w/out a VPN connection). Otherwise, there is no reason for you to install the WebConf Edge. It won't allow non-OCS users to be able to schedule meetings, you need to enable them for OCS to make that happen.
Regards,
Matt