Hey, Oro, I'll take a crack at your list ...
That the Templars made the Peralta stones I think the stones are a hoax.
That the KGC did not disband soon after the Civil War ended Officially, yes. Unofficialy, under the KGC name, about 1916. Since then, still active, especially in the 1930's (name unknown).
That the KGC used Persher code (some examples) Nearly all major 'lost mine/hidden treasure' tales, first appearing in newspapers, and later in books and magazines to establish false information surrounding bonafide cache sites.
That Jesse James was ever in Arizona Huge can of worms. Huge. Don't know where to start with this one. A lifelong project all by itself.
That the lost Adams mine and lost Waltz mine are one in the same Who knows? Couldn't say yes, wouldn't say no. KGC (name used for convenience) believers are some of the most skeptical researchers there are - adamantly opposed to the 'KGC' idea until, by their own observations, they 'see the light' and realize that if true, this organization was (is) composed of brilliant operatives capable of amazing things not the least of which is manipulation of public opinion.
From BB: can you give me a quick rundown on the Adams mine Nothing quick about this one. I have about 18 published/unpublished versions, nearly all of which are contradictory. The story begins in Arizona and ends in either Arizona or New Mexico. There's a lost gold mine. After that, take your choice of the version that suits your fancy.