Yamaha DTXpress/DTXplorer/DTXtreme

Hi Keith, 

Wow what a circuit! This is almost too discouraging for an electro-amature like me!
but I might give it a try anyway if you could help me with the following questions:
1) there is only a slight difference between the large topright and bottomleft circuits (the 
small bit just above IC2A). I would guess that I only need 1 of the two - but which one? Or 
am I completely wrong?
2) Is your comment about the reverse diode protection similar to the simple DTXPander 
circuit, i.e. just after the input-jack add a diode?
3) What is the small extra circuit just above that comment?

Meanwhile, I'm peptalking to myself to not give up... 

Thanks! 
Erik Paul