Easiest thing to do is look at twentyten or twentyeleven – each one a default WordPress theme – and see how comment functions are implemented in those. basically, it’s a comments.php file, a function in functions.php and a function call in a theme file, i.e. like your home.php.
You may have to revert to the standard WordPress loop, too, instead of the new query, which in your case has no advantages over the standard loop. There’s nothing out of the ordinary in your home.php file.