You should ask that in the other thread dedicated for working holidays in NZ.
https://forum.lowyat.net/topic/600789

Yea, I broke lots of tree branches recently while driving a 6 person campervan in NZ.

Really depends where you are going. If just walking trials, the locals even go barefoot. If you're going hiking, then hiking shoes. Otherwise, shoes that you are comfortable with walking long distances.

International driving license is no where near RM30 la.
I think that's a translation only.

And you don't need an international driving license to drive in NZ for a few weeks.

Driving around in a campervan is a real experience to have but I felt that it's not much cheaper than staying in holiday parks and motels. There are a lot more things to handle with the campervan, such as charging it, discharging your toilet, replenishing the fresh water, etc. If the weather is cold, it can be quite cold at night. Driving the campervan takes some getting used to it too. I did a short campervan trip once, but would definitely go for car and motels the next time round.

4 in a family, just nice for a car.

Yea there is. In Kaikoura I think. Can google that up

As long as you got roaming, you can use your Malaysian SIM card. But cheaper alternative would be to get a local SIM card.

No need. Our Malaysia license (new one with english on it) is sufficient.

If it's from NZ, nope.

I've bought Whittakers from NZ before, flew AirNZ to Sydney then Airasia to KL the next day. I declared that I was bringing in chocolates and the custom lady didn't even open my bag to check.

There's another thread for working holidays in New Zealand, please use the search function.

1 week? Just do South Island then. Pretty much whole of NZ is green and nature other than a few cities. You won't find cities like Singapore or KL there.

Extend your stay to 2 weeks if possible. It's very common for people to travel alone there. Do some research on backpacking in NZ.

Depends. Flight tickets budget around rm4k return.
How you gonna move around? Rent a car? Take bus?
What type of food? Eat out? Cook your own? If cook your own then you'll need accommodation that allows you to cook also.
I'm not sure how much is the average rates for hostels. Have to check that up on your own. You can search hostels booking websites for that.

If time is of no constraint, hire a car in auckland, drive down to south island, finish your holiday and fly 1-way chc-akl then back to kl.

January'17 is summer time. Long daylight hours and weather should be good. It's holiday season there though. School holiday, uni holiday, and adults holiday for Christmas sometimes they take a month off too.

Google up what you can do there. Auckland, Rotorua, Taupo, Bay of Islands, Cape Reinga, Hobbiton, Eastland, Wellington, etc.
http://www.newzealand.com/int/north-island/

Not a big fan of LOTR so didn't bother with the tour. Hobbiton was overpriced and not worth the money at all if you ask me.

5-7 days not enough to do much. Fly straight to Queenstown. Don't bother with Auckland.

Airasia flies to Auckland via Gold Coast. You'll have to take another domestic flight to CHC if you wanna head to South island. Refer to my post below:

Yes, direct flight is around 10 hours. 12.5 hours isn't consider "very long" for me if you ask me. Jetstar transit times are longer and the only direct flight to AKL is by MAS which cost RM3k+ minimum return.

If you book directly, you will not be stopping over at Gold Coast, you will only be on transit. You won't be able to get out of the departure hall. You don't need an Aussie visa.
If you wanna visit Gold Coast in the same trip, I suggest you better book AA flight KL-Gold Coast, then Air NZ/Jetstar/Qantas Gold Coast-NZ.

July.
Coldest.
Month.

It's less than an hour stopover and most likely you won't be able to get off the plane also. So I would say no, you don't need a visa.

Won't be flying to Auckland via AA until May/June.

Yup. This is normal.

Just make sure you get waterproof shoes. Not sure about the tracks though. You might be able to google and check the past years' condition. NZ has quite some info on their tracks online.

Quite true. If you are buying check in mostly for things like toiletries, it's very cheap in NZ.

But for those with lots of things to carry, no choice lor.

Google map is fine.

For moving around is Auckland: https://at.govt.nz/bus-train-ferry/journey-planner/

Where you using the old laminated driving license?

Your new Malaysian driving license is already dual-language and we can drive/rent cars perfectly fine with it.