Regarding black n white colour prints, are You selecting monochrome or black and white print when you are plotting? or may be your plotter can only plot black and white prints.
Regarding rendering - well ppl do use photoshop to render acad drawings to give it realistic effects. It is a little difficult (atleast for me) and you need to learn photoshop atleast little more than basics to do so. Try autocad impressions, personally I have not used it (it is available in limited countries), but I have heard that it gives more realistic affects than acad.