Design Phonegap App

I am looking to develop a PhoneGap application that will be deployed to Web, Responsive Mobile, iPhone and Android. The system will consist of: - MySQL Database - Java Web Application Hosting a REST API - JAX-RS as the RESTful API Framework - Persistence framework can be whatever you're comfortable with - Gradle as the build system - Asset integration to Amazon S3 (Upload and Query abilities) - E-Mail sending integration to Amazon Simple Email Service The UI portion of the App will consist of: - Landing Page allowing the user to signup or login. - Signup and login can be done through a web form or through facebook OAuth - if the user signs up with Facebook OAuth, we will connect the user to create the user account, then ask some extra questions including a username/password and items not collected from the Facebook API - Once the User is logged in they can manage their business by having CRUD operations on "Jobs" - A job to a user will simply be a data item they can have zero to many of attached to their account that will allow them to enter details about the job such as title, description, price range, pictures (which we will store on Amazon S3), visibility (true/false), etc... A full detailed SPEC will be provided. Once this Development work is completed, there will be opportunity to work on phase 2 enhancements for this project. The developer hired will need to have UI skill to make the UI look cutting edge and professional. Please estimate the amount of effort to create this system.