Freelance needed for redesign of our CMS CMS

Budget: $2,500 to $5,000

We are a swiss-based multimedia company and are looking for a UX/UI Designer to redesign our CMS and code the HTML, using bootstrap. 
Our CMS is called ScreenGate and it manages our installation screens which are dispersed by a variety of clients like: Restaurants, Gas Stations, Outlets, Buildings, Schools, Cinemas, etc… The screens display info related to the client needs and advertising. A screen can have more that one client and ScreenGate manages the areas.
We would like to improve the front-end, make it more user friendly, pretty and consistent, but we want to keep the same data structure, no new features will be added at this moment. Although the features will remain the same, some of its UX/UI can be improved, feel free to propose your ideas to make it better. The new redesign should also be extensible enough to add new features later.
If you are willing to take the job, how long do you need to complete the Design / HTML and how much will you charge for it? 
We'll give demo access to freelancers who we find interesting.Please show us some demo of your work if you contact us. We are particularly interested in people having experience in designing CMS or WebApps.
Thanks for your time.