Hi mate,
The details can be spoofed by altering the headers sent by the browser. Just the same as the referral page and browser version etc, can also be spoofed. For example, I could be running IE4 and I could send the headers to your servers so that it would think that I had IE6 or NN6.
The htaccess authentication is really easy to use and is just a case of setting up 2 different files on the server. The files are .htaccess and .htpasswd
The .htaccess goes in the directory that you want to protect and the .htpasswd can go in virtually any directory that you want.
To create a htaccess file, you can use a little script that I am working on..
This will create the htaccess for you and if you use Windows then it also gives directions on how to crate the htpasswd file.
Now, when that is set up, a user accessing the protected directory will receive a prompt to login. Once logged in, they have access to that directory and also any subdirectories without logging in again.
They only have to login again after they close that browser window, so even if they logged in, visited another site and then returned they would still be logged in.
About the seperate port issue.. If you wanted to do that then yes you would be better off setting the firewall to block all outside access to that port and this makes it much more secure as a port scan from outside would not even show a server running on that port..
Hope this helps Wullie