Circuit design(other than eagle cad)...

@d0773d yes, it's all a bit rough around the edges - but then it seems most of these tools are.

For the header, you could:

• drag out a dimension line to the length you want, then drag the header along to match that.
  
• Set the grid to exactly 17.78mm, the ctrl-click (it should then position the item actually on a grid point), and then drag it off one grid point
  
• Save the .brd file, open it in a text editor, find the reference to your component and just add 17.78 to the position :)
  
  

I need to look at KiCAD more, it seems good - just whenever I need to do something quickly (which it seems I always do) I tend to come back to Eagle because it's what I know.