Minor request

When you allow embed for Youtube and google maps ?

These will be included in different features. Youtube and other Video Embed URLs will be included in Media Uploader addon. Google Maps will be as a link embed and as a custom field.

It’s possible to make a function, when i made a reply to a comment to display automatically this form “in reply to userX” or “@userX” ?

There is not such an option.

How to add “You may use these HTML tags and attributes:” below comment area ?

put this code at end of theme’s functions.php file:

function my_comment_note(){
echo '<p style="font-size:13px; line-height:18px; padding:10px;">You may use these HTML tags and attributes: <code>'.htmlspecialchars('<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>').'</code></p>';
}

add_action( 'comment_form_after', 'my_comment_note', 10 );