Salty, unless I am missing something, this is about "reading" rather than "sales". If this is accurate it is down quite a bit from the 2014 "The Bible in American Life" by the Center for the Study of Religion and American Culture at Indiana University (55 percent).
Yes, I'd say that sales doesn't provide exactly what we need to know as far as "popularity" or reading is concerned. I have bought any number of Bible versions (even some I don't like) for various reasons, none of which I read on a regular basis (the one I do read regularly is KJV, though).
This is somewhat accurate. However, the translators did recognize that koine Greek was a different variety from classical. As I recall, they considered it a variety of the Attic dialect.
As for the papyri, those discoveries were made in the early 20th rather than the 19th century. The main changes because of the papyri discoveries were semantic, not syntactical. In other words, we learned more accurate meanings from the papyri, but not little more about koine grammar. Also, it is true that many considered the koine to be some "holy language" just for the NT until the discovery of the papyri.
I truly do not believe that the KJV translators ignored Hebrew for the LXX. I often read from the LXX (carry it to our college chapel), and there are many, many differences from the KJV, which is thus much closer to the Hebrew than the LXX is.
They did the best that could have been done at the time, save for those instances where would have preferred to not have King James influence some of their chosen renderings.
Actually, there is a similar attitude to the KJVO position in China by many towards the Chinese Union Version (和合本), of 1919 and in Japan, towards the Classical Bible (文語訳) of 1917. Interestingly enough, these Bibles were both translated from critical texts, not the TR.
In history, you also have Septuagint-Only movement, an Old Latin Only movement, and then a Latin Vulgate Only movement. Ironically, Augustine wrote Jerome urging him not to re-translate his Vulgate from the Hebrew because the LXX was already perfect! Turretin (1623-1687) argued against perfect translations in opposition to the Catholic teaching that the Vulgate was perfect.
"Now Nadab and Abihu, the sons of Aaron, each took his censer and put fire in it and laid incense on it and offered unauthorized fire before the LORD, which he had not commanded them." - Lev 10:1 ESV