Obviously the config file is not being saved. I'm not sure where it's suppose to even be saved.

The master is setup on www.incommonmedia.com - the installation of JMS went fine. Then I go to Manage sites and create a slave domain name - log into Plesk and create an alias for it on the master domain name - then I go to the installation and go through all the steps. Then when I go to the ACP or Site - it prompts me to install again... vicious cycle.

What am I doing wrong?

It loops because the "configuration.php" is probably not written by the Joomla Installation.
A potential reason is a permission problem.

You also have to check if at the end of the installation, Jommla does not prompt you that it has a problem to save the configuration.
Sometimes, Joomla prompt the configuration data into a text area that must be written manually into the "configuration.php" files that is located into the /multisites/xxxx where xxxx is the site ID.

Perhaps you will have to use the FTP Configuration parameter to grant Joomla with more permissions. See tutorial step 15 that show how to setup the FTP Layer.

it was the FTP layer configuration - was pointing to the default httpdocs directory and not the multisites directory for this slave site.

Ok it was the FTP layer that wasn't configured properly.


Next problem:

www.buggycountry.com/

As soon as the page loads you'll see the problem.

and all I needed to do was set the default template.


How come none of the extensions installed on the master site shows up on the slave sites?

When you create a fresh Joomla, you receive a new DB "empty" without any extension installed. You have to re-install the extension with exactly the same version than the one previously installed on the master website.
To avoid re-installation of the extension, JMS provide the possibilty to replicate a website.
You can define the website replication rules in the "Website template".
Once you have defined the rules, you can later use this "Website template" to create new website and this will also replicate all the content of the website given in template.
Therefore all the pre-installed extension will also be replicated.