@Adam:
1. I don’t know what is the level of customization that you have done. If you have customize the theme just using theme options panel, then all your edits will be safe. But if you have edit/added any files inside ‘catch-box-pro’ theme directory, then this will revert back to original when you update the theme.
So, we recommend to make the edit only from our Theme Options panel and other settings and not to edit any core theme files inside ‘catch-box-pro’ theme directory. And if you need to change any core theme files or functions then you need to build child theme and edit it.
2. There is one easy option to update the theme. Just activate our plugin Catch Updater. You can download and read the instructions from http://catchthemes.com/wp-plugins/catch-updater/
But if you want to use the FTP then you need to replace all the files and folders in ‘catch-box-pro’ theme directory.