Hi there.

1. Icon boxes: if you can send us your page URL containing the boxes and to be more precise which color and text you need to change? Even better, send us wp admin access in a private comment

2. You can assign a CSS class to the Rayden container in extra class name and then assign styles to it (width and height) in customizer -> additional CSS

Hello,

Just to clarify further from your screenshot I see the boxes with red background and black foreground and grey headers (Email, Address, Phone)

Is this what you are trying to achieve?

OK, assuming that you have a page with dark background and the background color is not a problem to make the foreground (text & icons) white you can add:

.clapat-icon {
    color: #fff;
}

.light-content h5 {
    color: #fff;
}

in customizer -> additional CSS. The last component of the icon box is the paragraph Email, Address which I assume you want to stay light gray

Even better you can assign a class to the wrapping container (so the block containing the icon box) and prefix the style selectors with this class