I worked in residential a fair few years ago. There were no breaks as such. We ate our meals together with the young people and actually these times were really important in terms of building and maintaining relationships.
We were allowed to have our phones and rules around them were as described above.
If you are completely new to this area of work here are a few bits of info which may be useful:
Your hours are 7-7. Be aware that you may not always finish on time. If a young person is having a difficult time you may need to stay and see things through. I mention this as you've mentioned you have children.
The were number of people who came to work in the place I worked who didnt see the shift out. One was a Scout leader who thought it would be an easy way to earn a living with all of his "skills". We were working with a particularly troubled group of young people at that time. Scout leader man was horrified at some of the language he heard and behaviours witnessed during a difficult time for 1 young person. He literally dropped his keys to the manager and walked out, never to return half way through his 1st shift.
Its likely to be one of the most difficult (emotionally and psychologically) and rewarding jobs you've ever done.
The young folk will inspire you, you'll feel sad and angry at what they've had to live through, but you will also have loads of fun! Its all about the relationships you build.
In my experience, the biggest issues were caused not by the young people, but by the other adults and the system. You need to be able to advocate fiercely for the young people in your care and be able to speak up when things aren't right.
I hope you love your new job! Good luck.