Everything you want to do can be done from within AutoCAD... but if you're a total beginner you may not have time to learn everything you need within the 30-day free use period.

You will be able to print to b&w by loading your dwg files into the free versions of Autodesk Design Review or Autodesk Trueview.  (Note that loading into Design Review requires an installed version of Trueview.)  Once you have these working you may be able to print to other formats such as PDF including black & white (monochrome) format.

Using the free versions will also give you the time you need to learn without time pressure. 

You can find links to both Design Review and Trueview -Here-

Dave.

If all you want to do is print in monochrome from AutoCAD use the monochrome.ctb or monochrome.stb plot style.

Caddymaster wrote: I am a beginner in editing and printing of dwg files. I have received many dwg ( probably autocad 2004/2007 based) and there are many layers in colour and origibnal drawing sizes up to A0. I simply like to edit such that all colours will change to black and I can print all different formats (A0 to A4) on an ordinary A3 printer. Questions: What program is best to buy or download? Can I work with Autocad 2013 I took from the web? or with a viewer such as Bentley? How do I chnage to B&W single colour? Many thanks for kind guidance.

Hello I propose to you usage of AutoCAD to plot your drawings.You should learn about some commands that make your plotting so easy and do not forget that the correct scale of printing the drawing is important too.
About the command take a look here.You'll also find how to make your scale correct:
How To Plot In AutoCAD


Edited by ivaylo2009 - 22.Nov.2012 at 12:31

The value of those sites goes mostly to the author for the advertisements.  The "information" on the page itself is pretty lame.  Frustrating would be another word.

Dave.


Edited by heinsite - 26.Nov.2012 at 19:22