Does your SSL work fine with the default WP theme Storefront for example? Can you try?
Describe me in more details what issues do you have with our theme? Do you have notices about content that is loaded using http?
Everything works fine when the parent theme is enabled. The problem appears once I enable your child theme. I suppose the problem is caused by some code in child theme functions.php. Check it and fix your custom code.
1) You don’t need to remove child theme. You just need to remove the incorrect custom code from child theme functions.php. If you placed styles to child theme style.css, of course, they will disappear once you enable parent theme. Move styles from child theme style.css to parent theme custom CSS to get them with the parent theme.
2) Because this font is custom font and it was removed. Once I have uploaded it again I don’t see any problem with it.