Categories of Language Styles

There are various styles of language within any tongue. They must
have been categorized by linguists long ago but I haven't seen it
discussed. Could someone give me the most accepted terms for these
kinds of language styles and point me to some texts that discuss them
in a definitive way including who the major thinkers were that
proposed/elaborated on them?

Taking English as an example I'll use stylistic examples that
predominated until the 1960s when everything became very informal. In
order of decreasing formality we have what I have called:

1) Formal, Heiratic Language (often in verse) that is almost never
spoken but everyone understands, e.g. King James Bible.

2) Formal Written (or Spoken Language although it often differs from
written). In English this would have included rules like don't use
contractions (use "it is" instead of "it's"), don't begin a sentence
with 'And', etc.

3) Informal but Proper Spoken (or Written): contractions are fine, as
are sentence fragments, etc. Words like "ain't" are not acceptable.

4) Highly informal, Colloquial, Slang, Common Speech often including
Dialects. "Ain't", "youse guys", etc.

Thanks,

Michael Donne