If the controller isn't included, I'd stay away from that deal. Often the servos used on robot arms use a proprietary system to run, and won't be compatible with other controllers. There is some software you might be able to use, but it's not the same as normal CAM software (like RhinoCAM). Take a look at Robotmaster, for example: Robotmaster CAD/CAM for robots (Off-Line Programming)
You should be able to use any spindle you want, but I doubt it would be rigid enough to cut metals. Foam shouldn't be a problem, though.
Be very careful when playing around with this thing, once you've got it moving. Unlike Cartesian machines, which operate within their own restricted spaces, these machines can "reach out and touch someone". It can easily kill you, even without a spindle or welder attached.