data communication

I'm having hard time figuring out what to do to my project were data communication is involve. Coz it has to accommodate more than 700 light sensors. And worst they want the system to be built as if it can automatically adopt to the changes like additional sensors and also the detection of the defective ones. I'm just starting in this kind of field in I.T.. What are the best i/o port to use? How will data comm accommodate all the sensors? And how can I determine the specific sensor sending a message that it is already been blocked (the light sensor I'm using is a Sensor Based Sentry) can you also incorporate sample codes with regards to the reading of the sensors. And also how can I call a program from a language like C to Visual Basic at run time.