Though the The Finished Mystery was published with the claim of being written by Russell it shouldn't really thought of as written by Russell. It was published after Russell died and it was prepared by others, though using prior writings of Russell as ideas for some of the content. Furthermore page 485 of the book does not claim that all of the members of the churches will be destroyed, since it says that some of them will survive. Not is says 'Also, in the year 1918, when God begins to destroy* the churches and the church members by millions, it shall be that any that escape shall come to the works of Pastor Russell to learn the meaning of the downfall of "Christianity." ' But it is true that even that sentence in the book makes a false claim. It also true that the WT/JW (at least during the time I was an active JW) teaches that virtually everyone who will survive the Battle of Armageddon will be Jehovah's Witnesses - implying that billions of other people will be destroyed.
Regarding your point number 19, neither Russell nor The Finished Mystery book says the earth was created 48,000 years ago. Page 139 of the book says "... the dawn of earth's creative week 48,000 years ago." Russell accepted the idea that there was (or might have been) a time gap between the creation of heavens and the earth (Genesis 1:1) and the start of the first creative day. Thus, while Russell taught the first creative day began about 48,000 years ago (the 1,000 year portion of Christ's reign was thought to be the final part of the 6th creative day - with each creative day being 7,000 years long), Russell (and even current WT/JW teaching) left doctrinal room for the Earth to have come into existence before the first creative day. The creative days are considered a transformation of an already existing Earth.
In the Studies In The Scriptures volume called The New Creation, in chapter one of that book, on page 18 Russell says "Examining the Genesis expressions critically, we discern that a distinction is made between the creation of the heaven and the earth (verse 1) and the subsequent regulations, or ordering of these, and the further creations of vegetable and animal life. It is these subsequent operations that are described as the divine work of six epochal days. Verse 2 tells us that in the very beginning of the first day of that creative week the earth was — though without form (order), and void (empty) —waste, empty and dark. This important item should be distinctly noted. If recognized, it at once corroborates the testimony of geology thus far; and, as we shall be obliged to dispute the deductions of geologists on some points, it is well that we promptly acknowledge and dismiss whatever does not need to be contended for in defense of the Bible. The Bible does not say how long a period elapsed between the beginning when God created the heaven and the earth, and the beginning of the creative week used in perfecting it for man: ..." On page 19 of that volume Russell says "We do, then, find satisfactory evidence that one of these creative "days" was a period of seven thousand years and, hence, that the entire creative week would be 7,000 x 7=49,000 years." See http://www.strictlygenteel.co.uk/newcreation/ncstudy1.html for chapter one of that volume.
I consider The Finished Mystery book to be largely written by Rutherford. Several of the books written in Rutherford's name make extreme failed claims like the one quoted above. A huge percentage of the Bible Student movement (a movement created by Russell) separated from the Watchtower society largely as a result of the publishing of the highly flawed book called The Finished Mystery.