Panopticon wrote:[1] the Israelite origin of the American Indian
[2] the future gathering of Israel and restoration of the Ten Lost Tribes
[3] the peopling of the New World from the Old via a long journey northward which encountered "seas" of "many waters"
[4] a religious motive for the migration
[5] the division of the migrants into civilized and uncivilized groups with long wars between them and the eventual destruction of the civilized by the uncivilized
[6] the assumption that all native peoples were descended from Israelites and their languages from Hebrew
[7] the burial of a "lost book" with "yellow leaves"
[8] the description of extensive military fortifications with military observatories or "watch towers" overlooking them
[9] a change from monarchy to republican forms of government
[10] the preaching of the gospel in ancient America
I have numbered your list so that I may address them.
I completely agree that in plagiarism cases, one looks for parallels and not unparallels. But, the most significant pieces of evidence are direct quotations and thefts of complicated story lines, as opposed to similarity of concepts.
For instance, as to items 1-4, 6 and 10, I point out that one of Thomas Jefferson's main motivations for the Lewis & Clark expedition was a belief that a group of Welsh Christians emigrated to the Americans and constituted upper Platte River tribes, the Modoks. The belief in Christian or Hebrew emigration to the Americas was a common theme amongst writers. For instance, Tennessee Supreme Court Justice Thomas Haywood in 1823 published an extensive work on archaeology in the Americans offering scattered proof of a Hebrew emigration connection to American Indians.
As well, Evangelical theology has sometimes included the belief that the gospel has been preached to the indigenous people of America, leading the all sorts of theories and justifications seen in Prescott's accounts of the conquest of Mexico and Peru.
So, these general theories have long been in circulation. Indeed, the Tanners cite these theories as possible explanations for a Book of Mormon rip-off of theories in place. So, Ethan Smith's book may have just repeated what was generally speculated to be true by people like Thomas Jefferson.