Rooney You can read relevant research findings on these questions in a good modern ergonomic textbook such as the one by Robert Bridges, third edition. In considering the alternatives, you need to take account of not only the standard data on light sources and surface reflections but also forms and sizes of typefaces, nature of tasks of operators, their heights and postures when standing and seated. To enable them to control risks, you need to issue clear instructions, supported by training and supervision. If you have more than a handfull of staff, it's worth doing well, as you risk a variety of forms of MSD and other injuries which can be painful and frightening for the employees and disruptive and costly to your business.

http://designingfortheweb.co.uk/book/ has info on colours, fonts etc. You should also consider disability issues