Work Order Manager

I am currently after expressions of interest in this project only and will advise when you can start. I need a system to manage work orders from my clients. These work orders are sent to me as an excel spreadsheet and I require a system that can import these files directly, either individually or by batch. The work orders, once in the system, need to be able to be assigned to a contractor. These contractors may be responsible for all or part of a job and once assigned a job must be emailed the details they need to complete their part of the job. This means that one job may have many contractors working on it. Once the contractor has completed the job they will report back to me and I will mark off their section as completed. After this has happened and all aspects of the job are completed I then need a daily report to be generated so I can send to my client. Once I have generated the invoice (done using seperate software) I need to be able to enter the invoice number, and once my client has a purchase order for me I also need to be able to enter that. At the end of each month I need to be able to print a report that states the invoice number, PO number and work order number to send as a statement along with the invoices. Once payment has been received I need to be able to mark off the job as completed and paid to then go into an archieve. The winning freelancer must have solid skills in PHP and MySQL, and the code must be 100% rock solid. Technical support must be able to be provided, especially when there is a system related fault. Any additions to the code have the opportunity for you to be hired to make these. All code must be neat, and commented. The winning freelancer should be able to provide evidence of their progress on the project and must strictly keep to their predicted finish date.