Glad to know that I've been able to help you. 
As for the rest.
Eco idle has ceased to work for me as well. I blame it on TP calibration since it was working before the cleaning was done. I am looking into this and will let you know the remedy when mine is also rectified.
Yes for the bad fuel average, please look into having the carbon cleaning service done it will improve your fuel average by a large margin as well as drive with a light foot.
Please have your gear oil drained. It's limit is 3.5 litres and will not take more. Since you have overfilled it, it stresses the CVT gearbox which is bad. The gear box is exactly the same for turbo and non turbo. (I have changed 4 n series cars both turbo and non turbos so can verify that 100%).
Who ever said that it takes 4 litres doesn't understand the car and their illiteracy can cost you a 40k gearbox in replacement! So please do drain out the excess 500 ml fluid.
A Mira condenser and radiator fit well on the n one. (Have that in my car as well). Yes the ac performance does die out on idle. 2 number gas if it would have been the case would have damaged your compressor by now since it makes the system run much heavier than its supposed to so don't worry out on that. If it's properly recharged it should work well.
Also regarding the fuel average, are you following the changing light pattern and trying to keep the peddle in the green zone than the white or blue? (Green is the optimum eco zone).