Hello,

1. Fonts: here is your settings https://prnt.sc/sb8s3y and here is the result: https://prnt.sc/sb8ro4 fonts are as per your settings.
When we change a font it doesn’t show immediatly or not at all. Clean the cache after each change and check again.

2. Please add this code to the Theme Settings > Custom CSS > Global:

body .basel-navigation .menu>li .sub-menu-dropdown {
    background-color: #999999;
}
body .basel-navigation .menu > li.menu-item-design-default .sub-menu li a{
    color: yellow;
}

5. I do not see black titles https://prnt.sc/sb91xg

6. You have this font here: https://prnt.sc/sb92y5

7. Please contact whatsap plugin support on this issue.

8.You can change the font by means of Advanced typography option, which allows to choose the item from a drop-down or insert your custom CSS class. Please navigate to the Theme Settings > Typography > Advanced Typography.

9. You will need to set the header with the widget area and add the custom code. Create HTML block with icons and add into the Area in the Header Widget.

10. You theme has been activated already.

Please create a topic for each issue separately.

Best Regards