Experience front-end developer required to support web app development

We're looking for a ninja front-end developer, expert in Javascript and mobile-optimized HTML/ CSS.

The application to be developed is an intermediation platform between service providers and service buyers.

It will be available through:

• A website, offering online as well as mobile-optimized displays;
• Mobile apps, built on the basis of the mobile-optimized version of the website and a mobile-app framework (such as Phonegap).

It will also be multilingual.

App will encompass the following key features:

• Detailed profiles of the service providers;
• Search and browsing of service providers’ profiles;
• Booking system allowing a buyer to book a predetermined time slot with a service provider, for a predetermined service;
• Providers’ calendar allowing providers to see appointments booked through the platform, as well as to input appointments they take outside of it;
• Messaging system allowing buyers and service providers to exchange messages on a one-to-one basis;
• Payment system allowing service providers to take credit card payments and deposits from buyers;
• Integration with a simple content management system allowing administrators to publish content to a dedicated section of the website;
• Buyers and service providers sign-up and account management;
• Admin management.

See complete list of features here:
https://www.wetransfer.com/downloads/33ba6cb53f0aa36f7219c438b68e191a20130705145146/515f8d36e0a2d1ab187dfdf5c11489c420130705145146/c2c52e

The back-end developer will provide a full JSON API to support all features.

Important notes:
• Please explain both cost & timeline in your proposal;
• Please distinguish cost & timeline for i) all front-end and ii) integration of the mobile-version in a mobile-app framework (Phonegap);
• Please mark the subject of your proposal with "[Appo]" to distinguish real from automatic postings.

Thanks and regards!