"Get a brew on" is rarely used in the USA as far as I know. On the other hand, the slang that you find "abominable" in your own words is quite common and accepted in English speaking countries not called England. A bit biased there on your part in my opinion.

Well "kick ass" and stuff was originally used in England-asses are known as stubborn animals who need kicking, if you want to get it moving- so, in its true meaning it's perfectly okay to use and to teach. Anyway, I know many educated Americans, who are more likely to teach the students not to ingratiate yourself as opposed to using 'brown nose'