When I was applying I was told by the board that you needed a minimum of a bachelor's degree and not necessarily in nursing, sorry for the confusion there. Then again things may have changed over the last year. Definately contact the Nurses Board of Victoria. With the amount of experience you have they might not require it, but the only way to find out is to contact them. I actually have a Bachelor's in biology and was in the process of finishing my MSN when I applied and had no problems. But yea, definitely e-mail them and I'm sure they could give you a straight answer.
Melbourne is awesome! I've been coming here the last 4 years because that's where my BF is from, so I can't speak for the other cities in Australia, but it's incredibly livable and diverse and accessible. I've had a pretty easy time settling in and found the Aussies I work with to be very warm and welcoming. I'm sure this is a trait you will find in any city though