tomaja

I saw that you have changed theme on your wp site so i cant look further, but still, the above code should work even on new theme.

Your posts should have excerpts with 55 words in them by default, so only thing you have to do is to remove more tag or <!–more–> from the posts.
For adding “read more” to excerpts instead default […] you need to add this function in to your childs theme function.php

// Changing excerpt more
   function new_excerpt_more($more) {
   global $post;
   return '… <a href="'. get_permalink($post->ID) . '">' . 'Read More »' . '</a>';}
   add_filter('excerpt_more', 'new_excerpt_more');

You are missing css for that icon, so you need to put

.icon-youtube:before {
    content: "\f167";
}

into your style.css file of your child Duena theme or custom css field in admin area. It is not good to change default Duena files because you will lose all changes after theme update.

Add

footer#footer a {
color: #F78C40;
}

in style.css file of your child theme or custom css field and change the color if you need to

You will need this snippet to make parental links clickable.

Maybe these one two snippets can help you out. You can also use text widgets in sidebars for custom content. Also check Codex page about ads.

If you set to show static page on the front page then you can set even front page layout to with left, right or both sidebars. Not to say that you can adjust sidebar layouts for each separate page or post.
Go to yoursitedomain.com/wp-admin/customize.php , then click on the “Front Page” tab and make the setting you want, e.g. choosing “A Static Page” in the “Front Page displays” option opens new “Set up the front page layout” option where u can select to view sidebar(s).

You can use this snippet