Write Some Software Magento

I have a project which has been started and needs finishing. It is 100% finished and works with PayPal. We need to work with SagePay Direct Payments now however. It is a Magento payment gateway we have created to accept credit and debit cards on our website. The gateway is an extension which can be dropped into any installation of Magento and it will work. There is another part which is adding functionality to a terminal which is sitting on another server. It currently changes it's functionality when certain variables are posted to it, it processes the card details sent to it with an authorization and tells the Magento extension the result. If successful, this is stored in a MySQL database which is already setup. We need the Magento payment gateway to have the options of using the same terminal to if necessary reauthorize and then capture transactions, void them if they were never captured and refund invoices online using this same method. The technologies and skills needed are: php, mysql, magento and the paypal api (nvp or possibly rest). There is one more step for this project, and that is we require all transactional post data to and from the terminal to be relayed through a secure SSL domain and hosting we will provide. So it will go: Magento Site -> SSL Domain -> Terminal On Other Server -> SSL Domain -> Magento Site and again in reverse.