Platform definition, cost & time Estimation needed: Webdesigner/Developer needed to define best technical solution (WordPress or other) for website and app design & programming (Wedding/Events Industry)

At this stage, the only goals of this job are to define the perfect, most cost-efficient technical solution to implement my project (if am optimal solution is proposed, you'll get the job to implement it). It may be WordPress, I also found a plugin that may serve as basis, or it may be another platform. Very important: friendly administration interface. After defining that, I want to understand what would be the milestones, how long it would take to have a beta version of the site and app and what the total costs of the project would be. Here is a short description of the requirements (full briefing will be offered upon signing a non-disclosure agreement): USER CATEGORY A needs the following functionality: Login Create Profile: name, address, phone, web, social media, text description, services, reviews, photos Upload temporary available products: upload photos and fill in form to describe products (colour, composition, tags, text description, available quantity), define validity dates and prices USER CATEGORY B needs the following functionality: Search (what users A have uploaded): tags, colours, dates, locations Book desired products (up to a certain date, defined as X days before the date mentioned by USER A), fill in form (based on chosen options, the final price is calculated and displayed), online payment, confirmation goes via e-mail/app buzz to USER A, B and admin, to trigger delivery. If the products submitted are not booked by any User B, they are automatically assigned to a predefined list of recipients, assignment list goes per e-mail to admin (and maybe a list of other recipients) to trigger delivery.