Idiomatic / regional slang translation is one of the main translation difficulties. If national colouring is present, then it gets only worse. So honestly I doubt very much most of these expressions can possibly have full equivalents in Russian.
"Losing one's religion" in the sense "losing one's temper" is "потерять самообладание", but it sounds way too bookish. The slang equivalent could be "взорваться", but, clearly it has no reference to REM. I don't know, can't think of anything else right now. Usually, according to the theory of translation, in such cases we should use description or calque translation. I don't think it would work in this case.
Even stable idiomatic expressions known for decades or even centuries rarely have their full equivalents in other languages, expecially if we are speaking of such different languages as English and Russian. So I don't think you'll find what you are looking for. There are simply no corresponding "terms", as you call them, in Russian.
Russian mat or some regional dalects (like Ukrainian or Moldavian) can't be translated into English either.
You need a native Russian speaker who's familiar very well with Southern American realia to be able to TRY to translate all those.
I don't have problems with English, and Russian is my native, but it takes me serious googling to sherlock the meaning of some words / expressions you mentioned.
Stil I'm not quite sure I got them. And I can't think of any equivalents.
Like, for "Americans" we have several slang words (америкосы etc.), but they often have negative connotation, so I don't think they are suitable at all. If the word "merican" was present in a text, in the official translation it would be "американец", unless it was used in a negative / sarcastic/ etc meaning, then the slang words could be used probably.
It is impossible to translate such words without a clear context.