By default, installing a new version of Office removes the old one. When installing, you need to tell the installer to preserve the older version (I haven't tried the Office 2013 installer, so I dont know precisely where this option kicks in). Even so, since only one version of Outlook can be installed, any previous version of that would be removed if you installed Outlok 2013.
Office Starter is available only as preloaded software on certain new PCs - it is not a product you can buy. It appears you can still download it from:
http://downloads.pcauthority.com.au/...office_starter