No it makes no difference where you add the extra inversion, in the fancy version it's before the split because I wanted a mixer at that point for the feedback loop.
You can use the circuit you posted, you don't need the 0.1uF cap, just connect the input resistor straight to the output of the previous opamp, use 10k resistors instead of 1M, and connect the + input straight to Vb, no need for the 560k resistor.
I should really get round to building the fancy one, I drew it up then kinda forgot about it.