Design Modern Flat Website Pages

We are looking for a designer to work with us to design around 30 to 50 modern, clean, flat pages for the back-end pages of our new website. The designer will need to be fluent in English (both written and verbal). They will need to produce wireframes (either actual wireframe using collaboration software or sketches of the page layouts) and all the UI design elements, form elements, etc. to a very high design standard for review and approval. Following this first stage the designer needs to produce detailed design mock-ups in Photoshop with all design elements organised in layers. Once each page design has been reviewed and tweaked (until we are satisfied with the design) it will be approved, at which time the designer needs to produce fully layered cut PSD files. Our back-end development team will then pick up the design files and do the rest of the HTML5 coding, etc, etc. We need the designer to start as soon as possible (yesterday). NO bootstrap design or previously used templates. The work must be one-off and fully custom. To be selected the designer must agree to do a one page re-work of an existing design for our website (at their own cost) so that we can decide who to work with. The designer who wins the job must be prepared to sign a Confidentiality Agreement and must agree to assign the copyright to us and NOT to use, post or publish the design concepts publicly (ever). The designer must also be prepared to use Skype and InVision for ongoing review and collaboration purposes. If you agree to be put to the test with the one pager please come with a quote (fixed price) for the design of (30 to 50 pages) fully layered PSD sliced files. Thank You