Where in the database or cache file does SS store this information?
In two separate files (per shopper) in the /ip and /moreip subdirectories of the ShopSite Data Directory. The location of this directory is up to whoever installs the ShopSite application, but you can see what it is in the Preferences -> Hosting Services menu. Note that the file in the /ip directory is just some binary stuff that you won't be able to read, but the file in the /moreip is a text file, not sure if the info that you are looking for will be in it or not, though.
Can we access this data via FTP or SQL?
This depends on your host and how the ShopSite software was installed. Some hosts will have this directory where it is accessible to you via FTP, some will not.
-Loren