Create Magento Payment Extension

We need an extension developed for Magento to allow payment by the Australian BPAY payment method (bank transfer). The features of the extension will be: - In the admin settings a biller ID should be able to be set. This needs to be able to be different for each website, ie multiple biller id's per installation. - Every customer who chooses this payment method for an order will be assigned a unique payment ID. The extension should allow in the settings for the preferred length for this ID to be. The payment ID will contain a check digit that is calculated using a LUHN algorithm. The payment ID should be unique per website. - On checkout the customer will select the "BPAY" payment method and then after completing checkout on the order confirmation screen payment instructions will need to be displayed. This will involve generating an image such as the file "[login to view URL]" attached. The biller code and ref in black are to be inserted based on the site biller id and the customer payment ID. - Also to be displayed on the order confirmation page is a QR barcode image that contains the payment amount, biller id and the customer payment ID. - An email should be sent to the customer after checkout with the same payment instructions that are displayed on the order confirmation page. - Functionality to capture the payment details once the order has been paid is required. In the admin, the customer payment ID should be able to be entered and it will display a list of orders that are waiting payment for that customer. The payment amount and transaction date should then be able to be captured. We require that no core files be modified. This should support Magento Community edition 1.9.