Adding features to an existing android app

I have an existing android application and i want to add couple of features , to start following are the features i want: 1. Simple List to have some selection options 2. Facebook Like chat screen which should come when user clicks on any of the options on the list. 3. Implement chat functionality with ability to upload, send receive photos. 4. One more component to show list messages which user can read and delete. Part time developers please don't apply, this is a very strict time based project and if the developer fails to deliver on the agreed time there will be negative feedback with deduction in payment. Apart from android development developer should also know GIT , which is a must for this project, as current source code is hosted on a server and can downloaded by GIT only. what i will provide : 1. Graphics assets 2. App work flow 3. REST APIs. 4. Existing application source code. If there is change is requirement then time for that will be calculated again. I want this feature for almost all android resolutions. If everything suits good i want to start the project asap. Happy Bidding