Lisbeth no need to be so deeply unpleasant and personal - I was trying to offer you helpful advice, but as it doesn't chime with what you want to hear you try to throw back handed insults at me 
Not that it is any of your business whatsoever, but I have been here longer than 5 years, primarily looking after my young children - 2 of whom were born here. I have kept my hand in with work by teaching a few classes, but now I try to ramp it up as the children get a little older, I find there is no more demand, and I talk to local EFL teachers and ones based in Munich and discover that even those doing best are self employed and making a fairly modest income - not enough to support a family or save, at Munich prices, and that those who were teaching mornings and evenings to fit around childcare have all found, like me, that there are no full time TEFL jobs, even the big firms who used to employ in house have all moved to employing free-lancers per hour.
I have met lots of people who seem to think they can teach English just because it is their mother tongue or because they have a degree, with no specific TEFL qualifications - there is no way of telling from your OP that you are not one of those naive people - it is not a case of "of course" at all.
If you want to take a 16 year old who doesn't speak German to Germany to live with you on the income from a job you haven't had a face to face interview for, let alone done a trail lesson, that sounds very high risk. There are plenty of schools who actually want to charge you up front for their own "training course" with "guaranteed work" to follow - but who are very cagey about the guaranteed hours or duration of that work...
There was no need at all to lash out with assumptions and personal insults at somebody trying to give you a helpful warning. 