any aussies that can help on the 7 3g

[bulldogs195461]

hope im in the right area,im completely green on this and would like some help,im really keen to get a nexus 7 3g,we have an android atrix phone and wi -fi with telstra.my question is how do i get the 3g component if i travel,to use my tablet can we put it with our existing plans,or could you buy a micro usb to connect it to 3g?if you can buy these usbs,do they have to be by a month or just till you use up what you brought.all help apreciated,also if 4 g comes in ,do they phase out 3g or will it keep going till no more devices are 3g compatitable.finally when they become available who is the supplier in australia for the nexus,
cheers john