Allowing comments in 5-star block

Anything that allows comments to be posted in a block would enable this, but since posting comments isn't the functionality of Fivestar, this falls outside of the functionality Fivestar will provide.

However, you can implement your own block that displays the comment form rather easily, using a custom block that contains PHP code:

$edit = array('nid' => arg(1));
print drupal_get_form('comment_form', $edit);

There's probably a module that provides this same functionality, but I haven't bothered to look.

I'm pretty sure I'm understanding you correctly. See screenshot of the end result of my previous suggestion.

Yes, Fivestar offers integration with comments, making it so that you can leave a rating along with comment, effectively creating simple "reviews". The way Fivestar does this is by modifying the comment form and simply adding in stars in addition to the normal "title" and "comment" fields. What you're asking for is a way to put the comment form in a block (which includes the Fivestar rating field by association). Because this deals with printing out the comment form, it doesn't make sense for Fivestar to provide this functionality, so you'll either need to find a module that puts the comment form in a block, or use the custom PHP code I posted above.

For testing, I also came up with code that should be used in the "Visibility Settings" for the block, using the "Show only if PHP code returns TRUE":

if (arg(0) == 'node' && is_numeric(arg(1))) {
  $node_type = 'story';
  $node = node_load(arg(1));

  if ($node->type == $node_type) {
    return TRUE;
  }
}