With regards to using LiquiMoly ATF to top up the power steering I would say that, although, it is a great product you should avoid mixing different brands of fluids. That is a general rule I follow on all my cars. In your case, the car has just 56,000km so I am guessing it still has the original power steering fluid with which it left the factory. If that is the case, you could go down to the 3S Toyota place and buy yourself a bottle of the stuff they sell and use that to top up the fluid.
With regards to the noise of the pump as you turn the steering from lock to lock, the slight noise of the pump and nothing to worry about. It is normal. However a loud whining/grinding noise indicates trouble. Not sure about the air bubles you have mentioned.