If lawyers have to pass a bar exam, does that mean they must become alcoholics?

It's not a requirement, but about 21% of them do so. No joke. Close to 1/3 suffer from depression too, but that doesn't typically set in until they've started their careers. 

i dont think so

Mormon Lawyers don't drink alcohol. (Supposedly)

Yes.

No, it means they must know how to make every alcoholic drink.  (Drinking them all then being able to crawl OVER the counter.. that's "passing the bar")

A principle in common law is "void for vagueness". The law must be simple enough and published in a place with free access so that an average person can read it and understand it. 

The American justice system is so vague that an entire industry exists to try to understand it.

They won't have to worry about it until they're "admitted" to the bar.

Not at all it means they have to pass the bar, not enter it.