Hey Sid,
The top questions that you should be prepared to answer in your PhD interview are:

What experience makes you a good candidate? How did you develop this proposal? What are your strengths and weaknesses? Tell us about a time you experienced a setback Why choose this field of specialization?

Although these questions may at first glance seem easy to answer, thinking about an appropriate answer to them so that the interviewers approve of you may be tough. check this blog(https://academicpositions.com/career-advice/10-common-phd-interview-questions) understand how to answer such questions and much more. If you need help with preparing for your interview, we have an amazing online interview analyser tool(https://ischoolconnect.com/contact-us) that you can try out by signing up (https://ischoolconnect.com/contact-us)with us for free :).

It is pretty hard to do a PhD without getting financial support from the school, and universities understand that! You get a monthly stipend and the tuition and health insurance is covered.
The school either rejects an application or grants admission with funding guarantees. In some rare cases, it does grant admission but offers only a partial aid.

Adding to what Juhi said, you will also (usually) have your health insurance covered as well

Ph.D.’s in NZ cost between $6,500 and $9000 per year