if you want to enjoy Altis 1.8 , go for Auto , nothing else. The gearbox is too noisy on the manual one, I drove mine 2007 1,20,000km on m2 and usually had to run between lahore during night, the car used to give me 13-13.5km/ltr with speeds not less than 140km/h
Ac on or off, doesnt matter at all, and BTW the brakes were absolutely fine on my car