Get user Account form
The second example won't work because user_profile_form() takes a user object as it's argument, not an id. I suspect your form is not being outputted because you're not actually calling print on it...render() just prepares the string it doesn't actually output it.

Try this code:

$account = user_load(1);
print render(drupal_get_form('user_profile_form', $account));


EDIT

You'll also need to include the user.pages.inc file where the function itself lives:

module_load_include('inc', 'user', 'user.pages');