Only 1hr connection time is very risky as Fiji time doesn't move very fast in the few times ive been to fiji it has taken up to an hour to clear customs and collect bags.

Air NZ will not probably check you bags on to Air Fiji
1: theres probably no interlining between the 2 airlines
2: Its Int to Dom so you will need to take your bags to get X rayed before they will be able to be loaded on your flight.

Also you may like to try booking on Pacific Sun (ex Sun air now owned by pacific) http://www.pacificsun.com.fj they are say that NAN-Taveuni is $125 +$16 VAT +$25 TAX