Modify and add functions on my app (Android and iOs) using Joomla

Hello, I have an android application and iOS using Joomla and PHP file for get JSON response from K2 plugin, I would like to add functions to my android application, this is what I want to add: - Change the logo and icon of the application (image 1). - Add the name of the vendor where you just find the product on the product listing page (image 2). - Add a tab to display a googlemap which displays the position of the seller. (image 3) - Add a "Submit product" menu available for all users of the application that is just a contact form containing fields (name of the product, categories, description, photo and the send button), all the fields will be send to the database for approval by an administrator. - Add a "Contact" menu that has sent a contact form containing fields (name, email, message), all the fields will be send to the email address on the application. Thank you, Full source code is available to you for changes in Eclispe, PHP file for get JSON response from K2 and cpanel with the url of the Joomla install with all admin details. my budget is 100 usd not more, and pay only when you made all changes.