Gas mileage is the same as it was with the 180* t-stat.
Operating temp for 6th gens is 170*F and the computer will be running the fuel system in open-loop until operating temp is reached. The computer will run the afr (air-fuel ratio) richer to warm up the enginer quicker until you get to op temp; then the outputs of the O2 sensor, etc will be valid. Above 170*F the computer will then try to maintain a proper afr.
Absolutely not true. Stock closed-loop enable is 43* F- I just chcked this by looking at my stock .bin.
There are other AFR correction functions in the PCM, but these are time based, not ECT based.
I do agree that a 180* thermostat is a better choice for most folks, but I want my junk as cool as possible when sitting in the staging lanes before making a pass.