What about a property in the Sounds?
Say so in the request. Water access changes both who can take the job and what it costs, and it is far better in the quote than discovered on the morning.
What if my flight is delayed?
Most operators track the flight and adjust, which is the main advantage over a taxi booked for a time. Give the flight number rather than a time so they can.
Is the price fixed?
For a booked transfer it usually is, agreed before the day. Ask whether waiting time, tolls and after-hours are included, since those are the common extras.
Can they take a group with luggage?
Yes, but the vehicle has to be matched to it. Say how many people and how many bags, because six adults with ski gear is a different booking from six adults with cabin bags.
Do they have child seats?
Many do, and New Zealand law requires appropriate restraints for young children. Ask for them when booking rather than on the day, and say the ages.