Hi fernandochen,
I don’t have any firsthand experience involving the kinds questions you’ve asked here, but there have been threads about this kind of thing in the past. I don’t know whether there’s anything in the threads that can specifically help you, but if there isn’t, maybe someone will come along later who can provide better help. Hopefully someone can also help you with the paperwork part.
There’s a thread from February of 2010 entitled “Public education for descendant children.” The original poster appears to be Brazilian. In his first post he wrote in part:
We shall probably go to Taipei, where all their relatives are. I would like to know if there are good public schools for children, and if there are any kind of special public education for Taiwanese children who are not Chinese speakers (my kids are 10 and 8 years old).
That thread contains advice and opinions. I can’t verify the accuracy of the advice, and of course, some of the opinions will differ from each other, but the thread looks like it would be worth taking a look at.
The thread is here: Public education for descendant children
There’s a thread from August of 2011 entitled “Enrolling Older Foreign Children in Local Schools.” The original poster wrote in part:
This topic has been under discussion a number of times, so I thought as we are in the process of doing this, I would post my first-hand experience. I’d like to make it clear that I’m talking about children older than kindergarten age, who don’t speak any Mandarin and who have little or no experience of Chinese culture, enrolling in ordinary public schools in Taiwan.
That thread contains some experiences, some advice, and some opinions. Of course, some of the opinions may differ from each other, and may even be in direct opposition to each other.
The thread is here: Enrolling Older Foreign Children in Local Schools
The situation in this thread, from July 2015, looks somewhat different from yours, but I’m pasting the link to it here just in case it can help:
This thread is from September 2010, and the situation in this one is also somewhat different from yours, but again, I’m putting the link here just in case it can help:
I hope someone comes along with more specific information and advice.