Oh right, I hadn't read the post carefully and didn't realize you were already in New Zealand. It's true that you have to be offshore to get the waiver.
Some companies do pay for some or part of the work visa or residence application. I would find out what they are willing to pay for and whether they are an accredited employer for WTR, for instance. If they paid for a WTR visa you could then lodge your application for residence in 2 years at a lower cost than if you were to do it now.
As for the other costs, if your husband gets a 3-year work visa (which is what we have) the kids get a visitor or student visa of the same length, depending on their age. It doesn't matter whether it's a visitor or student visa in terms of getting health coverage, just that it's more than 2 years. I'm not sure if a school-aged child who's homeschooled can get a visitor visa rather than a student visa. We had to change our application from visitor to student for my daughter because she was turning 5.