Online Estate Agency php development + Zoopla API integration

General information for the website: Buying online house selling packages
Kind of development: Customization of existing website
Description of every page/module: We have a site up and running using this theme http://themeforest.net/item/wp-residence-real-estate-wordpress-theme/7896392

We need to make a few changes how users pay for and build their customer package when selling their home plus also integrate the property listings with the Zoopla API http://developer.zoopla.com/ to publish houses for sale on there plus use the Rightmove.co.uk Automated Datafeed (ADF) for publishing properties to there also.

We basically need to replicate functionality as seen here - http://www.urbansalesandlettings.co.uk/seller-packages where users can purchase a package and also include bolt ons as per the tick boxes. Then make the payment with paypal. The theme itself already has some good functionality we can piggy back off to make this work flawlessly.
Description of requirements/features: Data to be saved in wordpress back end users will be able to sign in to their account section and view their purchased package then use the default theme functionality to submit their house for sale. We then need that to publish to other house search portals eg zoopla
Extra services needed: Customization, 3rd party integration
Specific technologies required: php
Similar urls: http://www.housesimple.co.uk/selling/signup
Extra notes: Ideal candidate to be from UK / London to assist us here in the offices in London....