Hello Steven
#1: You can find and open file plugins/system/jo_vm_autopost_facebook/jo_vm_autopost_facebook.php and go to line 119 and changed
$path_image = $baseurl.$post["file_url"];
To
$file_thumb = $post["file_url_thumb"];
$thumb = trim(str_replace('(Default URL)', '', $file_thumb));
$path_image = $baseurl.$thumb;
#2:
Go to line 86 and changed
$price = ' (Price: '.round($costprice,2).' '.$currency->currency_symbol.')';
To
$price = ' (Price: '.$currency->currency_symbol.round($costprice,2).')';
#3: We will check it
Best regards
Bach Pham