D1. Are my hard-worked settings kept during an update?

Theme settings (together with the Custom CSS and Custom JS field contents) are kept during updates.
File modifications (changes to style.css, to theme files or newly added files) in the theme folder are lost on update (this is default WordPress behaviour).

Consider using the custom CSS / JS fields or resorting to child themes for your extra customizations.

Important note: Since you can never have enough backups – and just to be on the safe side – use the Export Settings button (in theme settings) to save a complete backup of all theme settings before updating.