1--No, why? Do you expect your car to overheat? It probably won't. And, I haven't found a way to turn the AC off except by shutting down the entire system. The AC indicator light in my car only lights when the AC is manually turned on.
Provided the car was in good condition, you wouldn't want to turn off the AC. The power requirement is only about 2kW, and the engine should be able to cope with that. Our 1.3 Ford Festiva auto wasn't too happy on steep hills with the AC running, but you probably have more power at you disposal than that! Temp gauge should give you the information you need when tackling hills.
I can't comment on what "Auto" means in your car, but we leave the AC on all year round in our various cars, and the thermostat looks after the temperature for us. Can't remember when I last adjusted an AC setting, so I guess that's "Auto". One car that is consistently used around town gets 23 MPG (US) in the summer when the AC is definitely pumping, and 25 MPG in the winter when there's probably just mainly circulation.
There isn't really any benefit to playing around with the AC controls "on hills". The power draw is relatively small. Even the 4-bangers ought to be able to handle the additional load without you "noticing" on a hill. I just set mine to auto and forget about it. Mileage only seems to vary by 1-2mpg between keeping it set to "ice cold" versus "off" and that's in the middle of the summer. In more moderate temperatures, I'd expect the average load to be significantly less since the compressor spends more time being cycled off.