Here's what I've found in the meantime:
Lots of information exists when searching about "how to enable directory listing". Almost everything I've found suggests going to the website settings in the ISPConfig interface, going to the Options menu and under "Apache Directives" add something similar to the following:
I've done this, and what happens is it appends the above lines to the end of the configuration file for that vhost, just above the "</VirtualHost>" closing tag on the last line.
When apache restarts, the site still does not allow me to list the directory contents of the folder I created. The folder does contain both .htaccess and .htpasswd files.
If I console in, manually edit the vhost configuration file for this website, edit one of the above <Directory> entries to include "+Indexes" in its Options, and then restart apache - the site works just fine. However, once you make changes to the website in the administration panel, the vhost file gets rewritten and my change is lost.
Other information that may be relevant is as follows:
-Freshly upgraded to ISPConfig 18.104.22.168 (time to order a new manual, I believe, as Folders and Folder Protection were not a part of the previous manual I purchased!)
-Debian Squeeze OS (Followed the perfect server install guide originally)
-PHP for this website is set to Fast-CGI
-vhost config file can be viewed via the following pastebin.com link - http://pastebin.com/MJvRTLQQ
Thank you again for your assistance!