Customize header – top navigation area

Hello,
I have three questions.

I am using the Highend WP Theme. Is there an option to add a background image behind the logo and top navigation? I can’t find one.

Why wouldn’t the following custom CSS work (in the installed child theme style.css file) to add a background image to the header area? The image is not being found even using an absolute path. The paths are correct. I’ve tried many variations of
#header-inner-bg {
background-image: url(http://www.mysite.org/images/images/banner_bg.jpg) !important;
}

How can I change the global navigation section from dropping outside the header area when the browser window is resized narrower? Expandable sub-menus for mobile devices is enabled. The main header container is full width. I want to use Type 1 main header layout. It has the logo on the left and the global navigation adjacent and to the right of the logo. The global navigation menu stays on one line and when it has too many items for the header width, the entire list drops below and outside the entire header area. I would like the list items to wrap inside the header area, instead.

Thank you,
Terry