Any tips or advice, sailing from Auckland to Sydney in April 2015

Better to depart from Opua, rather than Auckland, to lessen the distance of coastal work up to Cape Reinga.

I suggest entering Australia at Lord Howe island - not only a great place to visit, but the local police sergeant can do quarantine, customs and immigration. You still need to go to a port of entry to get the final paperwork done, and I suggest Coffs Harbour as a friendly place to get that seen to. Remember to let the Australia authorities know your intended port and ETA more than 96 hours before arriving.