What is the average teaching load in research universities in New Zealand? I mean how many courses per academic year does a research active faculty member have to teach? Say, in Math or Science disciplines?
The standard load will generally be around 3 courses per year or equivalent, with 2-3 hours of delivered lectures per week per course. It is common to teach only subparts of courses and distribute the load over the year in that way. Usually there is a notional "student workload" by university policy for a course worth a given number of points, and working backwards from there determines the notional staff workload, but there can be some flexibility in structuring a course within that. The number of points per course can differ between departments.
Terms are generally twelve weeks long for the two main semesters, with the summer programmes and often summer courses themselves having idiosyncratic layouts (particularly because "summer" in New Zealand includes Christmas & New Year's). Many departments do not offer summer courses at all. The main semesters run approximately March-June and July-October.
There are generally tutors hired to run tutorials or labs and grade assignments and tests for all but very small or specialised courses. Those may be undergraduate students, graduate students, or full-time employees, depending on the department and course. In general exams are marked by the course lecturers themselves.
All of this can vary between institutions. In addition, there are certain parts of some universities that operate on a different model of courses, often with a larger number of shorter terms, and those will be different in numeric terms but likely broadly similar in actual workload.