Build an Online Store

I need some extra work on opencart which can summarize into following points : 1 . The template which I will use is : [login to view URL] 2. company users will come to website and get registered..then from front end they will add products.. Admin can see this all products..and once admin approve that much products will be displayed in front end 3. Only Admin can create categories & I will have three type of user ( Supper Admin :Full privilege , company owner : can add/edit products and data entry with each company owner: add only product ) the last 2 user's account will be renew every time . 4. Creating the classification 5. Controlling the frontage appering products 6. Controlling the Company account .. I need each company to pay for there account every year the payment cash and other small point which is not big problem