We would recommend looking at flights sooner rather than later so you get a rough idea of what the cost will be. You can book directly through Air New Zealand or United. There are a small handful of other airlines that also fly to New Zealand, that you can find with a quick google search. *Please keep in mind you will lose a day when travelling to NZ. This means you will technically arrive two days after you take off*
*You will need a valid passport, and NZeTA (visa). You can find the NZeTA at https://www.immigration.govt.nz *
Although public transport in Christchurch City is great, you will more than likely need a car to travel around. Especially if you are wanting to explore more than just the city centre. There are many car rental companies located at Christchurch airport. As a reminder New Zealand drives on the left-hand side of the road opposed to the U.S. right-hand side.
In terms of accomodation, there are a wide range of hotels available in and around the city, we would also reccomend looking at AirBNB to see what other options are available. We are more than happy to let you know what other guests are attending that you may know, if you want to figure out a group AirBNB etc.
Christchurch City is a great place. there are many activites including, museums, art center, botanical gardens, beaches, hikes, sporting events and a vibrant food/ coffee culture. However, if you are wanting to explore more of the South Island, we would suggest heading to the popular tourist town of Queenstown for a couple of days. Known as the adventure capital of the world, and one of NZ's best wine regions, there is plenty to do and see in this pituresque town.
We are more than happy to assist with any travel questions. Please don't hesitate to reach out!