wp_list_pages change of children and anchor of parent

You can use Walker: extend the Walker_Nav_Menu class in your functions.php

class custom_nav extends Walker_Nav_Menu {
  function start_el (&$output, $item, $depth, $args) {
    $item_output="<a href="" . $item->url. '" someattr="somevalue">' . $item->title . '</a>';
    $output .= '<li>' . apply_filters ('walker_nav_menu_start_el', $item_output, $item,  $depth, $args);
  }
}

and call it in wp_list_pages

<?php wp_list_pages(array( 'walker' => new custom_nav ())); ?>