Push Back for A320

[Donesh I.]

Today, while looking for photo opportunities around near the domestic terminal I noticed something very peculiar which I have never seen before. All jetstar A320's were pushed back with the tractor attached to the port main landing gear. My questions to the more senior and experienced members of this group are:

1. How does the aircraft get steered? Is'nt the nosewheel the controlling factor?
2. How common is this practice?
3. Is it limited to A320's and other smaller single aisle aircraft or is this practice prevailent among the larger behemoths too.

I am attaching a couple of pictures for your reference.

cheers