Port of established software to web service

We have a well established, highly reliable software package running as Windows software. We need to port this to a web service coded in C# / Asp.net / SQL. Current system uses around 70 data tables, and 30 supporting tables, 330 screens and dialog/editing boxes, 85 reports. The project will be broken down into completion of small sections with appropriate targets and milestones, eg. the coding of one screen and the associated couple of entry/edit screens. We expect you to be concentrating on the interface - we intend to code much of the backend in-house. You will not need to understand/decipher the current code. We would anticipate a short trial period to establish ability and compatible working relationship. If this goes well, we would continue until project completion, which could be up to a year. We would expect the project to use C#, Asp.net, MVC/Razor, SQL, Entity Framework, JavaScript, HTML, CSS, Bootstrap, jQuery. Reliability, documentation, clear coding, responsiveness and performance is key - no requirement for latest widgets, plugin controls etc. We will usually be available for discussion (in English) in UK working hours via Freelancer app, Skype, phone, screen sharing etc. Reference to previous work and expected hourly rate would be useful. Not too concerned about specific bids for the project (you'd need a full specification to have any idea on the workload/costs), as decision will be based on demonstrable capability, with payments firmly discussed at each stage either as completion of milestone, or hourly rates. Would expect ongoing commitment, submitting completed work every week, with steady regular payments from us.