Modifications of site for OpenCart

The site in question is [login to view URL] Please read all the points and give me a confirmation you can make the following work. If you have questions please contact us. SHIPPING Ability to change the shipping method based on the type of product : example: smartphone - delivery by courier cover - postal service ———————————————————————————— DATABASE How can I use a common database for many sites? Example, if the parent site insert a product or a category I would like to have the ability to automatically insert them into other sites. ———————————————————————————— RMA I need to be able to handle the RMA practices directly from the back end, however at this time the customer writes on the site and then everything goes via email ———————————————————————————- PRODUCTS We need two basic functions: - when I select a product color I want the picture to change - have the possibility to choose the product based on availability : Example if I select the white color must be able to choose if it is available 16GB - 32GB - 64GB and so on ———————————————————————————— ORDER - I would like orders can be managed more professionally - We can see right away what kind of product the customer has purchased Regards