/* Write here your custom CSS rules. */
<?php
if(!get_post_meta($post->ID, 'hide-author') || get_post_meta($post->ID, 'hide-author',true) != 'yes' ):?>
[.. author markup ..]
<?php endif;?>

<?php
if(!get_post_meta($post->ID, 'hide-date') || get_post_meta($post->ID, 'hide-date',true) != 'yes' ):?>
[.. date markup ..]
<?php endif;?>