First up, welcome to AFF, BVMS. Great to have you 'on board', but here's a tip: it's not a good idea to post your PNR and personal details online. I'd edit your post and remove them - if people want to give you personal advice they can use Private Messaging.
Now to answer your question. The answer is No, if you are transferring from an international to international flight at SYD, you do not need to clear customs etc. first. All you need to do after you land in SYD is find International Connections. From here, you'll clear a security screening (yes, liquids rules applies at this point, so take note) before heading up back to the departures level. If there are no delays to your inbound UA flight, 1h 40min (or 100min) should be sufficient time for you to make the connection.
There are a few caveats on this, though. Firstly, for this technique to work, you'll need to make sure that your bags are checked in all the way to AKL. If you can only check them in as far as SYD, then unfortunately you'll need to go through customs, claim your bags then re-check in. In this case, 1h 40min is a bit too short to make your connecting flight (e.g. if EK requires you to check in 60 min before departure, then that only leaves you 40 min to get your bags and clear customs - at that time of the morning, that's hardly enough time). Next, I'm not sure how UA and EK click together, but it'd be good if you can get boarding passes for both your UA and EK flight before leaving on your SYD-bound flight. If you can't do this, you'll need to collect a BP for your onward EK flight; the international transfer desks at SYD should help you with this.
Others here might have a better idea of what should happen. Otherwise, it might be a call to UA and EK.
thanks for the tip. I've written to [email protected] to ask them if the bags can be through checked or not. and yes, I did edit my post to remove my pnr #. thanks.