USPS October 30, 2014 K6 has updates for the November 2, 2014 changes that include previous updates for September 7, 2014

This module adds the ability to obtain the Online quote for First-ClassTM Package Service. First-ClassTM Package Service is not available for Retail.

Insurance is added to the:
$methods[] = array('id' => $type_rebuilt,
'title' => $title . $show_hiddenCost,
'cost' => $cost,
'insurance' => $usps_insurance_charge,
);

that can be used with an Order Totals module to make Insurance optional by customer choice. This would require additional customization to the:
/includes/modules/pages/checkout_shipping/header.php

First-Class Large Envelopes should be available on the USPS Production Server, once updated on November 2, 2014 by USPS. This can be tested on the USPS Test Server, prior to that.

Current version is available at:
http://www.zen-cart.com/downloads.php?do=file&id=1292