Hi,
I can't help with all your questions but will give you my eperience of moving here with a 14 year....she had finished 8th grade in the states which placed her into year 10 here in England. I think if I am right this is the age your youngest son will be.
In my opinion this is one of the easier times to move over with a teenager, a year or two later becomes more difficult. Year 10 is when they begin their two year work towards earning their GCSE's. My daughter is very academic and finds school easy in general. She adjusted very well, but she did find it frustrating in some cases. They learn some things in different orders- Maths seemed to be the biggest area for this, so she was ahead in some areas and behind in others. After the first 6 months she was pretty caught up and didn't have any academic problems. This was with help of a very supportive school. The other academic area that could have caused a problem was that all the children in her school were expected to do French GCSE....they had been taking french for many years. She had taken some Spanish, but Spanish wasn't offered. They excused her from this GCSE which allowed to her to have a study period to help her catch up where needed.
Socially she adapted wonderfully and in fact blossomed. The kids curiosity about 'the american' made it is easy for her to quickly make friends.
After GCSE's at age 16 children here go to a sixth form or ' college ' or work...the move more now is towards all of them continuing in some kind of education and if my years are right it will be that they have to by the time your son is here.
At sixth form or college (sixth forms are usually attached to a high school while a college is a separate school) they either take vocational courses or A levels. A levels are academic courses they choose 3 traditional academic areas usually. If they are going on to University this is the route they take. It is a 2 year program.
Okay that was a lot of information--- hope it makes sense-- please don't hesitate to ask questions!
As for court permissions- can't help with that because my daughter's father signed permission for her to come over, therefore we didn't have to go through the courts.
Buying a house I also can't help since my DH was here first already owning a home.
Good Luck through all the planning