copying out Hierarchical Select terms into other textboxes
You can use Drupal JavaScript API for setting the values of fields, based on selection made by user in Hierarchical Dropdown field.

The below sample code is for fixed number (3) of fields, you can further extend this to dynamically set the values of n number of fields using jQuery $.each().

(function($){
  Drupal.behaviors.exampleModule = {
    attach : function(context, settings) {
      // On hierarchy change event.
      $(".hierarchical-select .selects select").change(function(event) {
        updateFieldsValue();
      });

      function updateFieldsValue() {
        var First = $.trim($(".hierarchical-select .selects select[name='field_hierarchical_dropdown[und][hierarchical_select][selects][0]'] option:selected").text());
        var Second = $.trim($(".hierarchical-select .selects select[name='field_hierarchical_dropdown[und][hierarchical_select][selects][1]'] option:selected").text());
        var Third = $.trim($(".hierarchical-select .selects select[name='field_hierarchical_dropdown[und][hierarchical_select][selects][2]'] option:selected").text());

        // set value of Fields.
        $("input[name='field_prop_1[und][0][value]']").val(First);
        $("input[name='field_prop_2[und][0][value]']").val(Second);
        $("input[name='field_prop_3[und][0][value]']").val(Third);
      }

    }
  };
})(jQuery);


You can find more details about Drupal Behaviors on 'Better understanding of Drupal behaviors' and 'Understanding JavaScript behaviors in Drupal'.