[Sangetsu]

There's nothing wrong with taking a gap year if you think it will help in your studies or in another way. As you are studying Japanese, you might even get a few credits for time spent in Japan.

There is plenty of work available here for WHV holders, though it will be part time, and the pay will not be so good. The most common jobs are as bartenders, doormen, etc. Resort jobs exist, but are harder to get. Teaching English is the best option, but a limited one as well because of the short term of your stay.

As for the currency situation, it's bound to turn around soon. I'm not complaining at all, as I'm being paid in yen at the moment, it's going to make my winter vacation much more affordable. On that note, if you do find work here, even if the pay seems low, you have to consider how many New Zealand dollars you'll be able to get for your yen.

The cost of living in Japan is entirely relative. You can live here just as cheaply as you would in many other industrialized countries, though it will take an effort. Staying in a dorm (Sakura House, etc.), and eating from convenience stores or lower end food shops is very inexpensive.