I've been looking this over and it seems that the elements I want to change are these:
a different style for #sidebar-bg (which I could rename) to change the color of the sidebar)
<?php
echo avia_logo(AVIA_BASE_URL.'images/layout/logo.png'); (to change the logo image)
?>
#top .site-background, html, body, .comment-reply-link, .main_menu .menu ul li, .title_container #searchsubmit:hover, .isotope .entry-content, .image_overlay_effect, .tagcloud a, .news-thumb, .tweet-thumb a, fieldset, pre, .container_wrap .social_bookmarks li, #info_text_header.minimized {
background-color: #BDBDBD;
} (which is the main background color in the header.php file is called with this code: <body id="top" <?php body_class(avia_get_option('blog_layout')." ".$style.$avia_config['font_stack']); ?>>
Now, this is just a guess (and I'd like you to tell me if it's true): couldn't I create a different header.php file (say, say called header-2.php) and change the call to the header in my new template to:
get_header(2);
?>
If it's true I can create a new header.php for this section I would need to know how to point to the new style in this php (to change the background color):
<body id="top" <?php body_class(avia_get_option('blog_layout')." ".$style.$avia_config['font_stack']); ?>>