1) "Show Details" can be found here:
327 echo "<a class='button show_details_button $extraClass' href='".get_permalink($post->ID)."'>".__('Show Details','avia_framework')."</a>";
"Add to Cart" can be found here:
92 $label = apply_filters('add_to_cart_text', __('Add to cart', 'woothemes'));
I'm not sure why one is set in the plugin and the other one it the theme .. but changing this should work.
2) I don't understand your question, could you be more specific?