CamBam will do a great job with 2D dxf's and stl files from MoI.
I use it for mould work quite a lot.

It doesn't have 4th axis capability, but there is another program called CNCWrapper that will convert either the X or Y coordinates to rotary. Note that it isn't a TRUE representation of rotary like you'd get with dedicated software, but it's still very good.

CamBam is fully functional with 40 trials before it reverts to only producing ~500 lines of gcode, so if you leave it minimised to the Taskbar you've got plenty of time to get the feel of how it works.

Martin.