A simple way to control and monitor this system would be to use an Arduino. You can get control boards starting at $20 at radio shack, and they are scalable. There are plenty of sensors, interfaces, displays, and doodads to do what you are trying to accomplish. They are easy to program and debug, and lots of premade code and library files abound on the internet. You could put one together for your proposed setup for well under $100.
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