Android , Iphone and ipad App for shopping -- 2

Hi, I need two expert developer , who can work for me on site on my projects , on contract basis . 1. Sign up/Log in 2. Categories List 3. Products List 4. Product Search Option 5. Shopping cart 6. Payment features. 7. Map chatting Between admin and customers 8. Push notifications for buying products. 9. Backend API for products. 10)Conference Chatting with 2 different Customer with Admin as secret code language likes xxxxx then will be open it when write secret number via automatically 11)Search Map about Location of Products seller with seller full information(Tel,Add,PIC,Home page and etc) when click button at Products Details 12)then Chatting with Seller with Two Different Customer and Admin together Thanks ,