Hi Jacob, and welcome to Bimmersport! Not only have you bought the e46 (the best 3er IMHO), but you've also bought the best colour** too!
Excellent idea to ensure the cooling system is in good order, quickest way to turn an M54 into a boat anchor is to neglect the cooling system. BMW Coolant *only* - it's reasonably priced from Winger BMW. - accept no substitutes. If you join BMW Car Club NZ you'll net 10% discount off of parts on production of your membership card.
Re shocks, Sachs is your OEM part. You'll want to replace the fronts as a pair. There are other options like Bilstein Touring, or even Meyle, if you're after somthing that 'does the job' without going nuts on cost or performance. At 300+ kms you'll probably want to replace the strut bearing too, and some of the associated hardware/bushings etc. If you're in a hurry you might find Monroe or somesuch at Supercheap or REPCO. FCP Euro in the USA offer decent pricing and service, and you can expect your parts in a week or less at this time of year. what's my duty.org, xe.com, and realOEM.com*** are your 'friends' (great sources of info), if you start ordering online from abroad.
I warmly suggest you subscribe to the Wellington Events Room in order to keep abreast of what's happening. There is a good variety of events in the Wellington region, from coffee meets, cruises, road trips, and of course the monthly Pub Night (first thursday of every month) organised by BMW Car Club NZ wellington crew (Bimmersporters always welcome). Next Pub Night is Thursday 3 January, do come along if you can make it.
Hope that helps! Looking forward to seeing you at an event soon. And you should find plenty of help in the Bimmersport community!
** Disclosure: I've been running an Orientblau e46 325i Touring since 2012, including cooling system refresh, full suspension refresh, trans rebuild, braking system replacement, coils, other stuff I've forgotten, and general maintenance.
*** this is linked to your VIN sourced from carjam based on your number plate.
PS: cheap aftermarket badges are a false economy, delaminating quickly.