Theme Horse

@ChristinaMeade 1. The Leave a Comment is actually rendered by this function comment_form(). So, open the comments.php within the theme folder. Find the code <?php comment_form(); ?> and replace it with <?php comment_form( array( 'title_reply' => __( 'Give Me Your Thoughts' ), 'cleanretina' ) ); ?>. Hope this will help. Also, I would suggest you to make child theme to make this changes so that you won’t lose the changes when you update the theme.
2, 3. The color options, font family and size options is available in the pro version. So, you can upgrade to pro version if you like.