Port Denarau became an official port of entry to Fiji recently.
I booked 3 nights in advance from Tonga, this includes filling out and emailing a 7-page advance notice of arrival form. Be sure to copy the form to the marina as it makes life easier on arrival.
As it happens there was no room on any fingers so I was put on the last available mooring at Fiji$25 per night. I was approx 100 metres from the waterfront cafes, bars, etc. with a dinghy dock to tie up on.

I arrived at about 11 as instructed by the marina on channel 14, and was informed all the officials would arrive at 12, which they did! Very pleasant and efficient too, all done in about 15 minutes.
Fees were Fiji$165 for customs and $320 for garbage, Bio-Security, etc. As I didn’t have enough cash they were happy for me to pay at the marina office after a trip of about 50 metres to an ATM. The official walked over to the office to collect the cash.
There are no exit costs other than mooring fees.

The marina has a good travel lift and hard stand at reasonable costs, with power wash too. Baobab Engineering is an excellent on-site company with Yanmar and Mercury agencies amongst others. I used Ravmarine, note the name, to check out a VHF problem, and it seems to be OK.

The marina has all the usual facilities and despite being the full up and the high season we’re very helpful.