<p>I am new to FDM RP.  I've done a lot of work on ZCorp and Connex.  </p>

<p>The question is can vectors curve drive an extrusion nozzle?  Within a 3D volume I can generate curves that I want the print nozzle to follow. Is this possible or has it been done? If so, what software or is there a hack?  </p>

<p>Another question is, can you print a part with no sidewall or containment boundary?</p>

Vectors do not drive the extrusion nozzles in current software. There are methods to take vectors and create a solid model with them which can be used. The standard workflow is to take a solid model, save it in the STL format, and then import the STL file into the slicing software and outputs Gcode with contain coordinates for the extrusion nozzle to move to.
I have not seen any software that will create just the infill geometry without any bounding surfaces. This would be such a specific use case that it is unlikely to appear in current software. That is not to say that it couldn't be done, but you would likely have to implement such a feature yourself.