Add-ons for opencart administration

We need to develop some specific add-ons for a shopping solution in Switzerland. The system is based on opencart and the add-ons are for the administration of the shop system, as following: 1. Credit reform ([login to view URL]) automatic inquiry to gather data about the "bankability" of a client placing a large order. 2. Swiss Post tracking and registering packets for delivery, in use for back office only 3. Every order generates an invoice and a "payment slip": printing an order will send the print command of the invoice to one tray, and the payment slip is printed from another tray of the same printer Note: the current shop system and its back-end are already existing and are going to be renewed in a modern solution using opencart. The current back-end is in VB and the features 1. 2. and 3. are already existing in the VB program. The VB code could be a great help to develop the functions for the opencart solution in php.