Septuagint-onlyists

Many of these “Septuagint-onlyists” mock the reasoned defense of KJB believers even while clinging to the fairytale of a BC LXX for which there is zero evidence

Questions concerning the so-called septuagint.

What evidence is there:

1. for a B.C. Septuagint
2. that a B.C. Septuagint was widely accepted and used?
3. that B.C. Septuagint was commonly accepted and used by Jews?
4. that Jews would adopt pagan greek (used for commerce) for their religious studies and practices?
5. that if there was a septuagint as described in pseudepigrapha letter of Aristeas, that it was more than the Pentateuch?

Also:

1. Of the many variants of so-called septuagints, which is the authentic one?
2. Of the many so-called septuagint texts we have today, which one is based on mss that are older than codexes Alexandrinus, Vaticanus, and Sinaiticus?
3. Is there evidence of a Septuagint mss prior to Origin’s Hexapla?