Most low cost CAM takes 2D .dxf's, not 3D models. One of the best is SheetCAM. http://www.sheetcam.com For 3D models, a good choice is MeshCAM. http://www.grzsoftware.com
Keep in mind that for 2 1/2D work, such as pocketing and drilling, SheetCAM is a much better choice.
Rutex drives will work fine with Mach2/3. Start with Mach3 if you haven't set up Mach2 yet. Many more features.