Are those homemade Arduinos and a single pololu driver?
No there is three polou drivers and one arduino chip ( AT328 ) the other two chips are port expanders to get more I/O from the arduino.
What did you use to generate the G-code?
You can use inkscape, which is useful for engraving words.
But most of the stuff I either generated by hand straight into a text editor, or I wrote some helper applications in processing:-
http://www.thebox.myzen.co.uk/Mac_Apps/Processing.html
If I built the Reprap design would it allow me to use a version of software already developed?
Yes but then you would have to use a bigger ATmega chip than the 328