We just hosted a student from Italy, he left last week.
I think the things to consider when choosing a student/or choosing to host at all:
finances, AFS tells you it's like having another child, and that's what they mean. You will pay for all their food, family entertainment, gifts (like christmas, birthday) school fees, special clothing (like for the Alaska cold or sports) and school supplies. We put down on the application that the student would be responsible for his own entertainment, like our own kids (out with friends, movies, coffees, etc.) Our student did bring his own spending money, but teens sure can eat a lot, our grocery budget increased 35-50%.
Time: AFS has monthly meetings (not mandatory, and local) and 3 mandatory meetings the beginning of the year, the middle, and the end. For us we live quite a distance from Anchorage, which is the AFS hub for Alaska and it was quite the inconvenience to get him there for the mandatory ones (and AFS's reimbursement for travel is a pittance) They also have other outings planned thru the year that sometimes included the host siblings, and or host families, and sometimes cost something.
Also you need to be able to have transportation for the student after school if they are participating in sports/activities. (which AFS strongly encourages), and the time to see them in their games/programs.
Setting down the rules: AFS tells you to do this, and do it!!!! Every kind of rule you can think of, bedtime, computer time, what food is snack food and which isn't, homework time and place, etc. The rules can be lessened or eliminated once the student gets into the groove of your family. We had rules, but not many so there were a few that we had to address once the year started.
This year another of the AFS families in this area hosted a Thai girl (16-17), that was great. The family has 2 girls (8 and 13). The family seemed to mesh very well with her.
The Asian students tend to be a little (or more) reserved and are typically not demonstrative. But are good students, and polite and respectful. Unlike the Italian we hosted that was a big hugger! (who was a good student, but a big procrastinator)
There were actually 6 AFS exchange students in our area this year, and 8 from the different programs in our high school (size of about 480 students) A few too many I think!
All in all I don't think we would do it again, but it was well worth it for my son (17 y/o) Our family has had a rough couple of years and my DS really, really, really wanted to be an exchange student himself: I can not let go of him any earlier than I have to (he graduates next year

) so we compromised and got an exchange student. The 2 boys are already planning for my DS to vacation in Italy, and maybe meet up in the lower 48 for a vacation in a couple of years.
Hosting: there's good and bad.
You really need to KNOW WHY you want to host and can open your heart, family, and home to a child/teen for 10 months!
Good luck in your decision!
PS looking thru the applications...... Aren't the kids just amazing? so smart, talented, and brave...