WordPress Hide Show Content script and activate/deactivate script on screensize

For the WordPress question, I’d create a shortcode. Something like:

function expander_wpse_82811($atts,$content) {
  return '<div class="expander">'.$content.'</div>';
}
add_shortcode('expander_wpse_82811','expand');

Which your editors would use like:

[expand]Aliquam aliquet, est a ullamcorper condimentum... [/expand]

http://codex.wordpress.org/Function_Reference/add_shortcode