Page/2 posts don’t load and give 404

Never use query_posts() :). See this answer for more detailed explanation of why not, and the alternatives.

In this instance, remove your query_posts() and instead in a plug-in, (or functions php).

add_action('pre_get_posts','wpse57229_change_query_for_main_page');
function wpse57229_change_query_for_main_page( $query ){
     if( $query->is_main_query() && is_front_page() ){
          $query->set('post_type',array('etude','new'));
     }
}