Hi DantezGirl,
I don't know any marine tank people in Taupo, but if you headed up the road to Wonderworlds in Rotorua, you could have a look at their display tank.
Then you could can see what a sump, skimmer, pumps, live rock, etc look like in the flesh. But like I said before "don't take your wallet!"
Here is a link to the list of all fish (salt and fresh), corals and invertebrates that are allowed into our Country:
http://www.biosecurity.govt.nz/imports/animals/standards/fisornic.all.htm
That should answer your - can I get this in NZ questions
An RODI is just a fancy water filter unit that we use for our marine tanks to do two different things:
1. Replace pure water that evaporates (the salt does not evaporate, it stays in the tank)
2. Make up Artificial salt water for water changes.
The reason we use a water filter is so we don't introduce things like phosphates, nitrates and other greeblies that could cause bad algae to grow or hurt our tank inhabitants