your 2D drawings can be done with LazyCAM, that is included with Mach3, all you have to do is export the drawing from Autocad as a DXF file and lazycam will make gcode from it. As for 3D its a mine field, what is easy for one is not always so for another. Best thing is to down load some demo's and have a go. look at Bobcad, Rhino, Alphacam, mastercam, and onecnc, price will probably dictate your end result.
Graham.