Adding static text before paramters

The way to do that would be using a template. Check the example template on templates/default.php as a reference.

I couldn’t figure out how to do it using the template, but I was able to do it using css. To add “By” before the author:

Add this to the main css file:

.lcp_byline:before {
  content: "By: ";
}

Add this to the shortcode:
author=yes author_tag=span author_class=lcp_byline

Result:
By: Author Name

Hope this helps!