Raspberry Pi - What to Use it For

So I've been drooling over Raspberry Pi for ages now, and finally got one. Now I'm staring at it like it's a giant blank canvas.  What should I use it for?  The possibilities seem endless!

My thinking is that I have very high ambitions for Halloween this year, and I could really use a CNC router table capable of chopping up full sheets of plywood. I've always wanted to work on robots, and this seems like the perfect project to learn about it.  So... that's what I'm going to do.

I understand the concepts of CNC router tables: given a set of coordinates, one can use stepper motors to spin some threaded rod, which will push nuts which are connected to a gantry, thereby moving it back and forth.  Alternatively, one could use a belt drive.  In any event, a computer controls the motors and keeps track of where the router is. It raises and lowers the router, thereby controlling depth of cut, and moves the router in x and y, thereby cutting shapes.

So the questions I have are:

1) How easy (and cheap) is it to drive stepper motors using raspberry pi.
2) Can said motors spin large enough threaded rod to push a 4 ft long gantry a distance of 8 ft, and to push a router along the gantry?
3) Can I find 8 foot long sections of threaded rod in order to build a CNC router table that will cut a full sheet of plywood?

Only one way to find out!