The Admin scripts ARE the Rcon connection between the BF2CC Software and the BF2 dedicated server. The admin scripts only need to be installed on the BF2 Server.
In the case of R-Con Only mode, ALL BF2CC clients which connect have their own Rcon connection to the BF2 Server.
In the case of Daemon mode, ONLY the BF2CC daemon talks to the BF2 dedicated server through the Rcon connection on the local machine. In daemon mode all of the BF2CC clients connect to the daemon and the daemon is the gateway between all user commands to the BF2 dedicated server. Since the daemon is the only program talking to the BF2 server, it's easy to see how you can have the added features of user accounts, logging etc in daemon mode. It is NOT necessary to expose your Rcon port to the internet when running Daemon mode, but you will need to expose the Daemon port to the internet (default = 6712) so that the BF2CC clients can connect to the daemon.