Right--my theme isn't the problem. I have featured images with my normal blog posts & pages, just not with my product pages--it's something with the shopp plugin that doesn't have that. So when I have some more time, I'll see what I can figure out.
And for manually placing the code--I wasn't wanting to do it with js or css--some of the sharing plugins allow you to not place the buttons via the settings, and then you can manually paste the code into your theme, or where ever you want them to show up. For example, on my product.php page, this is what I had pasted where I wanted my sharing buttons to be when I was using the addthis plugin:
<!-- AddThis Button BEGIN -->
<div class="addthis_toolbox addthis_default_style">
<a class="addthis_button_facebook_like" fb:like:layout="button_count"></a>
<a class="addthis_button_google_plusone" g:plusone:size="medium"></a>
<a class="addthis_button_pinterest_pinit" pi:pinit:layout="horizontal"></a>
<a class="addthis_counter addthis_pill_style"></a>
<!-- AddThis Button END -->
So I was hoping I could do something similar with yours.