FYI: I'm not an electrician nor am I from australia. However, I did some reading to try and help you out. I came across a discussion on another forum. The OP was advised to NEVER wire led in parallel, for when one gets hotter, it uses more current, and when its cooler, less, meaning when either of these conditions occur the hotter bulb will steal current, leaving the other bulbs with less. The hot bulb will draw more and more as it gets hotter causing it to run even harder and burn out more quickly, allowing the other bulbs to draw more and well you get the picture. He also said to run one led driver capable of supporting all bulbs. So one driver for number of bulbs multplied by wattage. The OP happened to be wiring a set of three leds as well so it seemed relevant enough.
I belive the spdt switch is unneccessary.