How to change category, tabs, and button colors from the default red to the color I want.

Hi,
You can log in to Dashboard > DW Focus > General, add the following code to the Custom Css:

/*Change color for DW Tabs*/
.nav-tabs .active a:before, .nav-tabs .active a:hover:before {
    border-left: 6px solid transparent;
    border-right: 6px solid transparent;
    border-top: 6px solid #ba1616;
    bottom: -6px;
    content: "";
    height: 0;
    left: 50%;
    margin-left: -6px;
    position: absolute;
    width: 0;
}

.nav-tabs {
   background: #000;
}
.nav-tabs .active a, .nav-tab .active a:hover {
    position: relative; 
    color: #fff !important;
    background: #ba1616!important;
    height: 43px !important;
}
.nav-tabs li {
   margin-bottom: 0px;
}
.nav-tabs li.active a, .nav-tabs li.active a:hover, .nav-tabs li.active a:focus {
   border: none;
}
.nav li a:hover, .nav li a:focus {
    background-color: #111;
}
.nav-tabs li a {
    border: none;
    height: 43px;
    color: #fff;
}

.widget-title a:hover, .widget-title a:focus { color: #ba1616; }
.widget-title a { color: #000;}

.navbar-default .navbar-nav li a:hover, .navbar-default .navbar-nav lia:focus {
    color: #ba1616;
}
.widget_archive a:hover, .widget_categories a:hover, .widget_meta a:hover, .widget_pages a:hover, .widget_recent_comments a:hover, .widget_recent_entries a:hover, .widget_nav_menu a:hover, .widget_links a:hover, .widget_rss a:hover, .widget_archive a:focus, .widget_categories a:focus, .widget_meta a:focus, .widget_pages a:focus, .widget_recent_comments a:focus, .widget_recent_entries a:focus, .widget_nav_menu a:focus, .widget_links a:focus, .widget_rss a:focus {
     color: #ba1616;
}

.navbar-default .navbar-nav li a:hover, .navbar-default .navbar-nav li a:focus {
    color: #ba1616;
}
.widget_archive a:hover, .widget_categories a:hover, .widget_meta a:hover, .widget_pages a:hover, .widget_recent_comments a:hover, .widget_recent_entries a:hover, .widget_nav_menu a:hover, .widget_links a:hover, .widget_rss a:hover, .widget_archive a:focus, .widget_categories a:focus, .widget_meta a:focus, .widget_pages a:focus, .widget_recent_comments a:focus, .widget_recent_entries a:focus, .widget_nav_menu a:focus, .widget_links a:focus, .widget_rss a:focus {
     color: #ba1616;
}

/*Change color orange-red to red #ba1616 - slider et tabulations*/
.dw_focus_widget_news_slider .carousel-entry .cat-links, .widget_news-slider .carousel-entry .cat-links {
    background: #ba1616;
}

.dw_focus_widget_news_slider .carousel-title-indicators li.active:before, .widget_news-slider .carousel-title-indicators li.active:before {
    background: #ba1616;
}

/*title color orange/red #ee3224 to red ba1616*/
.home .hentry .entry-title a:hover, .home .hentry .entry-title a:focus {
    color: #ba1616;
}

.home .hentry .entry-title a {
    color: #000000;
}

.dw_focus_widget_news_list a:hover, .dw_focus_widget_news_list a:focus {
    color: #ba1616;
}

.dw_focus_widget_news_list a {
    color: #000000;
}

/*Color red category pages, Single posts & search results, side bar widgets (title, author, comments, date.. etc)*/
.hentry .entry-title a:hover, .hentry .entry-title a:focus {
    color: #ba1616;
}

.hentry .entry-meta a:hover, .hentry .entry-meta a:focus {
    color: #ba1616;
}

/*Color red top menu - bar navigation */
.navbar-default .navbar-nav .active a, .navbar-default .navbar-nav .active a:hover, .navbar-default .navbar-nav .active a:focus {
    color: #ba1616;
}

/*Color red news ticker*/
.dw_focus_widget_news_ticker a:hover, .widget_news-ticker a:hover, .dw_focus_widget_news_ticker a:focus, .widget_news-ticker a:focus {
    color: #ba1616;
}

/*navigation next, previous post in single post*/
.post-navigation .nav-links a:hover, .post-navigation .nav-links a:focus {
    color: #ba1616;
}

Also, you can change the color for some section as header, footer and Typography section in the DW Focus option. However, in case you can not change the sections that you want to find, you can open the dw-focus.css & dw-focus.min.css in the \wp-content\themes\dw-focus\assets\css folder or you can tell me detail about the position that you want to change, I will help you.
Hope this helps !

The custom CSS worked fine. Thank you! However; I really liked how this color was configurable within the DW Focus template previously, and hope that setting comes back in the near future.

One related question, is there a way for me to change all button colors too, like the "Subscribe" button in the lower right?