You can add custom classes to each post. Here is a quick example of one approach:
add_action('post_class','YOURNAME_post_class');
function YOURNAME_post_class( $classes ) {
global $wp_query;
if( ! $wp_query->is_main_query() )
return $classes;
$classes[] = 'class-on-all-posts';
if( 0 == $wp_query->current_post || 0 == $wp_query->current_post % 3 )
$classes[] = 'class-on-every-third-post';
if( 0 == $wp_query->current_post || 0 == $wp_query->current_post % 2 )
$classes[] = 'class-on-every-second-post';
return $classes;
}
You can then tweak the image and div alignment css based on the post classes.