Impact of the upgrade process e.g. Catch Box Pro 2.1 -> 2.2

Hi Guys, Firstly I love the Catch Box Theme, Thanks. Sorry for the very newbie question but I would like to better understand the impact of the upgrade process e.g. Catch Box Pro 2.1 -> 2.2. I have only modified options available in the theme… eg. Sidebar widgets, menus, theme options, header and background, etc. I have a few items in custom CSS styles. The upgrade process states (after b/up) to copy the new files up via FTP or (WP admin) activate another theme, delete the Catch Box Pro theme then install the new CBP theme. Do either or both processes remove all my modified options and design changes listed above? Deleting the theme suggests to me it would revert back to the default options? I have read the FAQ but not certain what constitutes “modification of core theme files”? If I need to redo all the modifications I expect it would be much better to do this via a child theme to prevent this in future. Also is there anything else I should do prior to the upgrade like disable all plugins, etc? Thanks for your assistance WildlifeTravelPhotography.com