After the visa interview, do I need to pay the semester fees or the overall course fee before applying from here, or can I pay by semester in New Zealand for a Master's?

You are generally required to pay the full tuition fee before submitting your student visa application for New Zealand; paying by semester is typically not an option for international students. If you use the 'Approval in Principle' (AIP) route, you can submit your application first and pay the tuition fee after you receive the AIP notification. Given your background in Civil Engineering and your recent master’s in Information Technology Management, being ready to pay the full fee up front will help ensure your application process is smooth.