$order = Mage::getModel('sales/order')->load($orderID);
if ($order->hasInvoices()) {
    $invIncrementIDs = array();
    foreach ($order->getInvoiceCollection() as $inv) {
        $invIncrementIDs[] = $inv->getIncrementId();
    //other invoice details...
    } Mage::log($invIncrementIDs);
}

$order = Mage::getModel('sales/order')->load($orderID);
foreach($order->getShipmentsCollection() as $shipment)
{
    Mage::log($shipment->getData()); //get each shipment data here...
}

$productId = $_item->getProduct()->getId(); //for order emails
//$productId = $_item->getProductId(); //for invoice emails
$product = Mage::getModel('catalog/product')->load($productId);
$attributes = $product->getAttributes();

//Get a list of all PRODUCT ATTRIBUTES you want to show in this array...
$dispAttribs = array('hardrive', 'memory', 'processor'); 

foreach ($attributes as $attribute) {    
        $attributeCode = $attribute->getAttributeCode();
        if(!in_array($attributeCode, $dispAttribs)) continue;
        $label = $attribute->getFrontend()->getLabel($product);
        $value = $attribute->getFrontend()->getValue($product); 
        echo "<br /><strong>" . $label . ":</strong> " . $value;
}