RFP Sourcing Website

I want to create a site where purchasing companies can post their RFP (Request for Proposals, RFPs and similar) and then supplying companies can submit bids against the RFPs. Although the principle is largely similar, please note that this is not a freelancer website but more of an e-procurement or e-sourcing website. The process will work as such Purchasing Company 1. Register 2. Create a new request for proposals and upload related documents 3. Create questions associated with request for proposals 4. Publish request for proposal in either of: a. Publish to all registered suppliers to view and respond b. Publish and selected some suppliers from database to view and respond 5. RFPs are time based 6. Receive responses from supplying companies and review 7. Select winner Supplying Company 1. Register 2. Create their supplier profile and upload company profile 3. View requests for proposals submitted by purchasing companies 4. Respond to RFP by submitting proposals. Other features • Payment will be required to publish and/or respond to requests for proposals – just paypal and stripe • Each published request for proposal will have something like a project clarification board – where supplying companies can ask questions and receive answers from purchasing companies privately or publicly • Only registered supplying companies can view details of request for proposals • Ability to upload documents • Request types with slights difference in form fields - Request For Quote (RFQ), Expressions Of Interest (EOI), Invitation To Register (ITR), Request For Information (RFI) and Request For Proposal (RFP) • An admin backend to manage everything • Email notifications based on events and activities