CNC machines are expensive, but are incredible. The only one I've worked with came with its own software, so I don't know if you'd buy that separate or not. Anyways, what you do is you go in and design what you want. The one I used could only cut into flat wood like a 2x4 or something like it.
But, you'd go in and design something, set different cutting depths if you wanted. Then, you could set what tool you'd be using, such as a ball end or flat end. You'd then send it to the CNC/Lathe and it would write the program necessary to make the proper cuts.
Hit go and it would cut.
But, as said before, you're talking BIG bucks if you plan on getting one, especially if you want to make bowls and the such. You're also talking about lots of time, effort, and wood to do stuff.