Managing content display on the main page of the site

I'm trying to get my content set up such that the latest post always shows the full content, and the later ones only show excerpts. I've updated postformat.php with a loop as follows:

...
<div class="post-bodycopy cf">

<div class="post-date">
<p class="post-month"><?php the_time( 'M' ); ?></p>
<p class="post-day"><?php the_time( 'j' ); ?></p>
<p class="post-year"><?php the_time( 'Y' ); ?></p>
</div>

<?php if (have_posts()) : $count = 0;
while (have_posts());
$count++;

if ($count == 1) : the_content();

else : the_excerpt();

endif;
endwhile;
endif;
?>

</div>

...

The problem here is that:
1. It's echo'ing some of the code to be rendered in the browser (count++, count ==)
2. It doesn't seem to work as expected - it renders the content in 3 sections for each post with multiple duplicate sharing buttons.

It's the standard mullet loop taken from this site:
http://perishablepress.com/easily-ad...oop-templates/

I'm kind of at a dead-end with it - I've tried a bunch of different formatting things, like having each line of code individually start with <?php and end with ?>, but that functioned 100% the same as the above.

Is there someplace else I should be writing this code, or something with Montezuma that would prevent it from working?

I'm new to Wordpress/PHP - so apologies if this is a basic error. Thanks in advance for any help.