I actually don't drink coffee, alcohol or tea, but as many people know, I am a very non social and strange person who... how do I put this... doesn't always get along with others. I work alone, I keep to myself and though I do socialize, I think thrusting myself in such a social church will, well I will crack and shatter.
It seems more a lifestyle (and to many, as I have seen, brings joy into their lives and they are grateful for the church).
Hopefully for you, you are not like me and can function properly with people all the time,
I am pretty sure, to answer at least one of your questions, Missionaries are from, I think 18-26