Hi,
i think i am the right person for this project. The main reason is simple: i had many projects Raspberry pi related in the last year. As a matter of fact I just finished a project a few days ago. I know how to work with raspberry, i ran into many problems with it (drivers that do not work, functions that work one way on x86 and another way on ARM, ...). I see you mention PHP as the programming language. If you don't have a strong reason for it i would say Python is much more "pi" friendly. Also with Python i can code the whole app to be a full screen app (that would be good for you i think, both from a visual standpoint and also because it would stop anyone from messing with the system in any way). I have a few other ideas (some from previews experience). Please let me know if you want to hear them.