Love the idea of the book- I'd have a few stories to tell. Over the years in Leics I must have hosted 100s of foreign students, some on a paid basis, some on exchanges, some of our assistantes at school, some from other schools, friend's kids and their friends's - and later for the few years I run my language school from home, hosting 6 teenagers at a time from at least 3 different countries/languages, so they would have to speak English together ... I hosted many from Nice, only to realise a few years later that they were all children of National Fron leaders- and they asked me to be their official host- I declined 
No time to write about the attitudes of French teachers now- they basically came in 2 camps- those with clearly racist à la Front National, and those who at the opposite end were quite left-wing and truly believed in the French principle of secularity, including education- and genuinely believed it was their duty to protect girls from their parents. Going out, but will come back to this when I have time- a fascinating subject, and the attitude is so different to the UK one.