if albums are deleted through ftp, does this screw up the database? Say I have information filled out for an image, or album of images... does zenphoto adjust to that or should images always be removed through admin?

No, zenphoto is generally filesystem based and will check if the database matches the actual content of the albums folder. It then updates itself. But you can additionally hit the "Refresh database" button on the admin overview page to clean left behind orphaned entries (can happen sometimes).