The good news is - Koru lounge access was no problem in Hamilton on the 31st of Dec. The DJ check-in staff did have some issues with the PIN number, which supposedly changes daily, but we were in by 5am-ish.
The lounge itself was unattended, and access was granted using the DJ supplied PIN (hence the potential for extended opening hours). The lounge is quite small (as you'd expect). Apart from 1 couple who came and went, we were the only lounge users. An AirNZ staff member popped through once.
Food was limited; some cereals (rice bubbles, muesli) with milk. I found a toaster in a cupboard, but there was no bread. There was a fruit bowl consisting of apples and some very ripe bananas, and quite a few snacks such as jaffas in a jar and a variety of biscuits.
Drinks comprised juices, some soft drinks and milk. There was a coffee machine but it didn't have any milk connected to it - which didn't bother me as I don't drink coffee.
There were 2 PCs and a printer together with wifi - though the wifi was so slow that I ended up using my 2degrees SIM for some iTunes downloads. I can't remember if there were 2 or 3 large screen TVs - all off, but able to be turned on using the buttons on the TVs (I didn't spot any remotes).
Given that I wasn't counting on getting lounge access, I was pleasantly surprised. There also didn't seem to be an issue with access for all 5 of us (wife + 3 kids), but I guess with PIN based entry, you could let in a football team once you were in.