Ok a few comments regarding your tank set up:
-Chillers are expensive, often noisy and they consume a lot of power. If you are cool with those things then get a refrigerated one (not a peltier[SIZE=-1]) as they are better at cooling. How hot does your tank get? Like how much do you need to cool it by? Also bare in mind that it is often much cheaper to order a chiller from the US than through a pet store here but you might need to convert it to work with Australian power as many of them don't. This isn't hard to do if you know any electricians! Else you could probably take it to a place like Jaycar.
Not sure where in Australia you are but if money is a concern then I have found using ice bottles and fridging my axolotls to be adequate for summer.
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-Unfortunately it is very difficult to maintain live plants in an aquarium with axolotls. Plants need light, and axolotls are nocturnal and need cooler waters. You can use aquarium lights but if temperature is a concern then don't use lights, which usually means you can't keep plants alive.
- PVC pipe/cave - just get one big enough for your axolotl to hide in, pick one you think looks nice
- Spray bar - is your filter current strong? If not, don't worry about a spray bar. If it is, then you can buy spray bars from an aquarium though they are a bit of a rip off as you can make them yourself. There are many ways to make them yourself but my friend made them by getting a piece of plastic tubing and poking holes in it, then fitted to the filter. I found a pic on another thread of something similar:
http://www.caudata.org/forum/showthread.php?t=52065&highlight=spray+bar (check out post 7[SIZE=-1])
Hope that helps!
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