iPhone Application development - Store finder

I need an iPhone application designed and developed. The concept is to help users find a food store (details to be provided later) within their proximity based on their location which would utilise GPS or the user entering their Postal Code. It will initially be based on a type of fast food store in Australia. A database of all stores names, location and postcode will be provided. I have begun building this already. The application should enable users to simply launch the app, use GPS to determine their location and on instruction, push back to the user store locations in terms of those closest / within a 2km radius and directions to the store. I envisage this would interface with Google Maps. Finally, the app should allow users to rate the store based on a 5 star rating and add review comments and upload photos of the store / experience. I will provide a logo for the brand and it will be linked to a website which exists today. I would like the app to be downloadable froma site and from iTunes. I have minimal knowledge of the application development option so a recommendation is requested to move ahead along with an outline of what will be provided and what differentiates you from other developers. The site and concept it light hearted and any proposal should keep this theme central and top of mind. An opportunity to take over the existing website development and management may be available upon successful completion of this work. Timing, a proposal within a week (by 27 June) and 1 month to develop, test, modify and launch. Please respond with any questions. Thanks and regards