HTML/CSS designer as a team member

I tried to hire a designer for a short one-off project for this work but it would appear I need a designer that can work as part of our team for few months - 1 to 3 months for a PHP/SQL product that is already on the market. Designer will need to work on each page, drill through and pop-ups for all different user accounts.
We have a web based application developed on PHP and MYSQL. This application front end UI is now old, and we need to update it with tweaks (we cannot afford major disruptions). As Page by page is converted developers will be engaged to modify any PHP coding needed.
If you have the credential and experience to work with a team of developers remotely, then please submit your bid.
We require the following:
1-You must be a good designer with original ideas yet prepared to work together with the owner to shape up the overall vision initially.
2-You must understand what is best for user experience on web applications to advice our team
3-You must be available to work on fast schedule and turn around. Our team is scattered around the world, USA, Egypt and India. You will need to jump on already busy team.
4- I will be looking for clean, not cluttered interface design... Attached is the current look that will needs updating to make modern and professional.
5- you must be dedicated to the project where you are available to discuss and show progress on a daily basis.