Change order of form fields & html email message

Hi, I was wondering whether it is possible to configure the order of the default and custom form fields as displayed at de front end.

Another thing: In order to create html email messages I added some php code to functions.php as described in your FAQ, but this doesn't seem to work.

How can I use HTML in emails?
Appointments+ uses wp_mail function and HTML is disabled as default. To enable HTML in emails, add these codes inside functions.php:
function app_modify_headers( $headers ) {
return str_replace( 'text/plain', 'text/html', $headers );
add_filter( 'app_message_headers', 'app_modify_headers' );