yes each airlines company has their own membership/mileage program 好像网站主页上能直接加会 yes. i think usually the online enrollment is free. and you can get a membership # even without booking any trip 一直没用过,不知道有啥收费之类的么? i don't think there's any fees (for most programs). 先买 yes you can get the mileage after you book the trip