Firstly, for answer of how to add multiple images on product info page on zencart, please refer to http://tutorials.zen-cart.com/index.php?article=58

Then, if you want to make multiple large images instead of thumbnails on product info page , edit file YourSiteSource/includes/modules/additional_images.php, replace the following lines(First back it up!):

$products_image_large = str_replace(DIR_WS_IMAGES, DIR_WS_IMAGES . ‘large/’, $products_image_directory) . str_replace($products_image_extension, ”, $file) . IMAGE_SUFFIX_LARGE . $products_image_extension;
$flag_has_large = file_exists($products_image_large);
$products_image_large = ($flag_has_large ? $products_image_large : $products_image_directory . $file);
$flag_display_large = (IMAGE_ADDITIONAL_DISPLAY_LINK_EVEN_WHEN_NO_LARGE == ‘Yes’ || $flag_has_large);
$base_image = $products_image_directory . $file;
$thumb_slashes = zen_image($base_image, addslashes($products_name), SMALL_IMAGE_WIDTH, SMALL_IMAGE_HEIGHT);
$thumb_regular = zen_image($base_image, $products_name, SMALL_IMAGE_WIDTH, SMALL_IMAGE_HEIGHT);
$large_link = zen_href_link(FILENAME_POPUP_IMAGE_ADDITIONAL, ‘pID=’ . $_GET['products_id'] . ‘&pic=’ . $i . ‘&products_image_large_additional=’ . $products_image_large);

// Link Preparation:
$script_link = ‘<script language=”javascript” type=”text/javascript”><!–’ . “\n” . ‘document.write(\” . ($flag_display_large ? ‘<a href=”javascript:popupWindow(\\\” . $large_link . ‘\\\’)”>’ . $thumb_slashes . ‘<br />’ . TEXT_CLICK_TO_ENLARGE . ‘</a>’ : $thumb_slashes) . ‘\’);’ . “\n” . ‘//–></script>’;

$noscript_link = ‘<noscript>’ . ($flag_display_large ? ‘<a href=”‘ . zen_href_link(FILENAME_POPUP_IMAGE_ADDITIONAL, ‘pID=’ . $_GET['products_id'] . ‘&pic=’ . $i . ‘&products_image_large_additional=’ . $products_image_large) . ‘” target=”_blank”>’ . $thumb_regular . ‘<br /><span class=”imgLinkAdditional”>’ . TEXT_CLICK_TO_ENLARGE . ‘</span></a>’ : $thumb_regular ) . ‘</noscript>’;

$alternate_link = ‘<a href=”‘ . $products_image_large . ‘” onclick=”javascript:popupWindow(\”. $large_link . ‘\’) return false;” title=”‘ . $products_name . ‘” target=”_blank”>’ . $thumb_regular . ‘<br />’ . TEXT_CLICK_TO_ENLARGE . ‘</a>’;

$link = $script_link . “\n ” . $noscript_link;
$link = $alternate_link;

to:

/**$products_image_large = str_replace(DIR_WS_IMAGES, DIR_WS_IMAGES . ‘large/’, $products_image_directory) . str_replace($products_image_extension, ”, $file) . IMAGE_SUFFIX_LARGE . $products_image_extension;
$flag_has_large = file_exists($products_image_large);
$products_image_large = ($flag_has_large ? $products_image_large : $products_image_directory . $file);
$flag_display_large = (IMAGE_ADDITIONAL_DISPLAY_LINK_EVEN_WHEN_NO_LARGE == ‘Yes’ || $flag_has_large);
$base_image = $products_image_directory . $file;
$thumb_slashes = zen_image($base_image, addslashes($products_name), SMALL_IMAGE_WIDTH, SMALL_IMAGE_HEIGHT);
$thumb_regular = zen_image($base_image, $products_name, SMALL_IMAGE_WIDTH, SMALL_IMAGE_HEIGHT);
$large_link = zen_href_link(FILENAME_POPUP_IMAGE_ADDITIONAL, ‘pID=’ . $_GET['products_id'] . ‘&pic=’ . $i . ‘&products_image_large_additional=’ . $products_image_large);

// Link Preparation:
$script_link = ‘<script language=”javascript” type=”text/javascript”><!–’ . “\n” . ‘document.write(\” . ($flag_display_large ? ‘<a href=”javascript:popupWindow(\\\” . $large_link . ‘\\\’)”>’ . $thumb_slashes . ‘<br />’ . TEXT_CLICK_TO_ENLARGE . ‘</a>’ : $thumb_slashes) . ‘\’);’ . “\n” . ‘//–></script>’;

$noscript_link = ‘<noscript>’ . ($flag_display_large ? ‘<a href=”‘ . zen_href_link(FILENAME_POPUP_IMAGE_ADDITIONAL, ‘pID=’ . $_GET['products_id'] . ‘&pic=’ . $i . ‘&products_image_large_additional=’ . $products_image_large) . ‘” target=”_blank”>’ . $thumb_regular . ‘<br /><span class=”imgLinkAdditional”>’ . TEXT_CLICK_TO_ENLARGE . ‘</span></a>’ : $thumb_regular ) . ‘</noscript>’;

// $alternate_link = ‘<a href=”‘ . $products_image_large . ‘” onclick=”javascript:popupWindow(\”. $large_link . ‘\’) return false;” title=”‘ . $products_name . ‘” target=”_blank”>’ . $thumb_regular . ‘<br />’ . TEXT_CLICK_TO_ENLARGE . ‘</a>’;

$link = $script_link . “\n ” . $noscript_link;
// $link = $alternate_link;
**/

And add line(if you upload large images to main directory):

echo “<img src=\”http://www.YOURSITE.com/images/{$file}\” />”;

before the following line:

// List Box array generation:

Now save and refresh the product info page of zencart, you’ll see the fancy!

Paypal has a restriction(Paypal does not allow your country of residence to ship to the country you wish to) that if the client buys an item when their billing address & shipping address are not in the same country, paypal will refuse the payment due to paypal seller protection policy. But sometimes a customer may buy a product delivered to a friend whose shipping address will not be the same as his billing address.

To solve this, if you’re using paypal Website Payments Standard – IPN, you can do via the steps below:

go to PAYMENTS > “PayPal Website Payments Standard – IPN” > Address Override, Set the address override to “0″. If you set it to 1, the address in Zen Cart overrides the Paypal address (the billing address), so when when it compares the addresses, if they don’t match exactly, you get this error.

And, if you’re using PayPal Express Checkout, set Express Checkout: Require Confirmed Address to No, and then edit the file below:

YOUR_SITE_SOURCE/includes/modules/payment/paypalwpp.php:

change from $options['ADDROVERRIDE'] = 1; to $options['ADDROVERRIDE'] = 0; Please note that there’re two occurrences in this file which needs modification.

After the modification, the customers will now be able to set their billing address & shipping address to different ones.