how to get started with stepper motors and hall effect sensors

I am trying to build a machine for cutting out sinks here at my granite shop. I am pretty handy with the mechanical side of things but this is my first project to get involved using arduino. I don't know where to start so i figured I would reach out and see if one of you out there could help me get this ball rolling. I have built a machine that will rotate 360 degrees and follow a template of the sink cutout. What I need to do next is figure out the best way to incrementally drop the router bit down a specific amount after each rotation of the cutting . I am thinking of using a stepper motor that would rotate a number of turns ever time a hall effect sensor would sense a rotation. If anyone has any suggestions i would appreciate your expertise...

graniteman74: I have built a machine that will rotate 360 degrees and follow a template of the sink cutout. What I need to do next is figure out the best way to incrementally drop the router bit down a specific amount after each rotation of the cutting.

Can you use a mechanical system that uses the movement between your rotating machine and some fixed point to work a screw adjuster?