Working Visa and job without demand?

Hello there,
I was thinking about emigration to New Zealand and working as baker, because this job is actually on http://skillshortages.immigration.govt.nz/
Problem is that in my country there is no such thing as certificate level nor baker school for people in age of 20.
So I was thinking that I would go to NZ on tourist visa, then I would find a job as assistant baker and in this way I would get experience necessary to pass exam for New Zealand Certificate in Baking Level 4.

The questions are:
1. Could I get Working Visa as assistant baker?
2. If I couldn't find this kind of job for a longer period of time, would I get Working Visa for being, for example shopkeeper or fisherman?
3. If I won't be able to get Working Visa from such jobs, then what is the best way to legally spend 2 years in NZ, which is needed for Resident Visa?
4. Those Certificates are really new thing for me, and I'm not sure how do I get them. I just need to pass exam or the only way to get them is to go to NZ's college?

You better check with NZ Immigration if this information is not on their website. In my opinion if you are able to get a job here you cannot study because you have a work visa and not student visa. If you study here you need a student visa and you can work 20 hours a week whilst you study provided your course is of a certain level, also you need to check which course with NZ Immigration or the institute you intend studying. You can also then work full time during their semester breaks. The only problem is to study here its expensive as a foreign student and you should be able to afford it. If you do not have a qualification as required by immigration a job is not enough to get you residency. This means that you need to get points for your qualifications which have to be a certain number of years to gain points. I have a freind from France she has a degree BA and a certificate course in catering. She works as a pastry Chef but cannot get enough of points for her qualifications as her BA is not in line with her work experience and her what she is currently doing in NZ if she had a three year diploma in catering she would have qualified.