1. I need control RDP Session, how i can read the logfile to know when the start session and when is the end of RDP session during Openvpn
Do you want to control RDP session (ie disconnect, or connect to some session) or only want to know when RDP session started and ended?
2. I want setup the openvpn server to close the client openvpn session after 15 minutes that Client is idle on this session
OpenVPN is not intended to disconnect tunnels if there is no traffic. Its like turning off the LAN switch, because all computers are idle, or users are watching some movie. OpenVPN insteed has mechanism to keep the tunnel up.
3. I want prevent client using auto-reconnect, every time client want to connect, they must type the password
On OpenVPN client config file add: "--auth-retry interact".