Question about my LS2

[French Fred]

Hi,
I've swapped one LS2 into my 1968 Camaro. So far, I haven't plugged in the CO2 sensors, and the engine runs well. My question is, may I damage the engine? Should I plug them for better combustion?
Another question is, with the CO2 sensors, is it possible to tune the engine to use E85 fuel, and what must I modify to run E85?
The last question is: when I bought the car, the engine was already done; now which software are you using to tune the engine?
Thank you so much for your help.
Fred