If you mean config_mp.cfg this is in your COD 'Main' folder. If you mean the server config file I spoke of in my tutorial on setting up a server, you can either create one yourself, or go to the website I recommended. It is a Server Config Builder. Find that here: http://www.noginn.tsohost.co.uk/codserver/ Just fill in the blanks and it emails you a copy. Then, just place it in the COD 'Main' folder.
Go to the website and find out. It's easy - just fill in the blanks.
Go to http://www.whatismyip.com/ it will tell you your IP. Are you on a static IP address? I suspect you're not, so that means it's dynamic - everytime you log onto the net your IP will change. This is a bit of a problem when you're running a server, as you will have to keep changing your server config file. YOU NEED YOUR NETWORK DETAILS ENTERED CORRECTLY IN THE SERVER CONFIG FILE - OTHERWISE NO ONE WILL BE ABLE TO FIND YOUR SERVER LISTED