Opencart developer for multiseller services marketplace

Note that this is a service marketplace. Customer is supposed to book service for a time slot which can range from hours to days. Opencart 2.1 + multimerch extension is already there in place working fine. What i need you to deliver is : 1. Custom product definition form for seller - So that he can define services/events which can happen daily, weekly, weekends. For daily services, he should be able to define time slots - and quantity and price for each bookable time slot. He should also be able to provide a date range in which the services will be unavailable. 2. At customer end, customer should be able to choose date using datepicker (and time slot - if applies) to make a booking 3. Payment gateway config. 4. SEO 5. UI customization - removal of all unnecessary UI elements from seller as well customer pages like removal of extra product configuration options apart from the use case. Replacement of all product related terminology with service related terminology for example - "Add to Cart" replaced with "Book Now". "Delivery address" -> "Billing address". 6. Theme selection and application - suggestions expected on what theme to apply. And application of the same. 7. Overall look and feel of website.