Here
https://www.immigration.govt.nz/empl...al-skills-visa are the INZ instructions to an employer thinking about sponsoring a foreign applicant for an Essential Skills visa.
1 and 3. The answers derive from those instructions. If it's a skilled job in line with your qualifications, on the essential skills list, the employer can sponsor you with no further formalities. If it's a low-skilled job, he would have to prove that he had been unable to recruit any NZ national or resident, or, at least, nobody suitable, before being able to sponsor you.
And here
https://www.immigration.govt.nz/empl...ited-employers are the notes for accredited employers.
From these, you will see that the answer to your question 2 is no - the Talent (Accredited Employers) visa requires that salary threshold.
4. If a job arises in a different skill area from your qualification, you are unlikely to be able to get a visa from it, because you have to be able to show you are qualified - you can see that from the INZ website pages about the Essential Skills visa. However, some jobs, as described in ANZSCO, quote a number of years' experience as being acceptable in place of a paper qualification. If you did some other work before going to study, then it's
possible you might have enough experience to count, but you would have to have the evidence.
If the job is a low-skilled or unskilled one (and this edges into your question 3 as well), INZ are not keen to grant visas to foreigners for such (as there are plenty of unskilled and low-skilled NZers who need to make a living), so they would apply the labour market tests very strictly. If INZ find that there are NZ applicants or potential applicants within the area who could be trained to do the job, they will not allow a foreigner a visa for it.