Resolved questions
2 Questions plz plz!!!!!!!!!

换可不可以=can i exchange/change or not?
到站=arrive at the station
收到信=letter of having received
到上课的时候=when it's time to start class
一张床=one bed
会知道的=can know
应该找钱=should give change
路上车很多，可能晚一点！=there are so many cars on the road, might be a little late

for your first sentence you can make it more clear by saying 那部电影是哪国的?
second sentence is reasonably correct, but you can also say 他是一个日本留学生