I recently spent over 5 months tramping in NZ and it is definitely going to be a great trip for you. Be sure that you get the Annual Hut pass (something like US$65?). It will pay itself off in about two weeks or so--after that everything is free in the backcountry huts (more like hostels).
I am assuming that your list is for everything--both town and trail. If this is so, every single hostel will stash extra gear for you while you are away on the tramp--we used our day packs to hold all of our town items. Worked great.
Depending on where you plan on going, you may not really need the tent. My girlfriend and I used our tarptent not nearly as often as we had originally thought (and we hiked almost every track except for the Milford). It is great for privacy and extra options, though.
I agree with ditching the swimming shorts. You can also most likely ditch the GPS, especially if you are hiking the traditional tracks. We were able to use map (can be rented at local DOC offices) and compass for cross country sections of certain trails. Does your leatherman also have a knife? Use your watch alarm instead of bringing the travel alarm. Ditch the cotton socks for something synthetic. You will most surely be wet, often, but every night you can dry things out in the huts (cotton maybe not so quickly?). Use a gallon ziploc and some sheets of paper that can be resupplied between tramps--10 oz to carry around for a notebook is excessive. I hiked in pants the whole time (the sandflies are UNREAL!)--if you like this you can leave the shorts at home. If you plan on hiking the Dusky Track you will probably want to use knee high gaitors. The mud on certain tracks is waist deep (I'm not exaggerating at all), and anything to help keep the gunk out of your shoes will help. And you should plan on hiking the Dusky Track--it isn't nearly as hard as everyone will tell you (UL hasn't caught on yet in NZ and we were told repeatedly by locals that we were going to die--while we were passing them) and is absolutely incredible.
On average, if you are experienced, you will be able to do every track in 2/3 the time posted. Let me know if you have any questions at all and have a great time.
PS--I just read your last post and noticed that you'll be wwof'ing (sp?) there mostly--whoops.