First of all, kudos for your interest in Appys and wanting to someday join those who are dedicated to preserving the breed.
Unlike with Quarterhorses, "foundation" can mean a couple different things with Appys.
To hardline Appy folks like myself, a "foundation" Appy is one that is primarily of true Appy blood that predates the formation of
ApHC, and displays the conformation, characteristics, and abilities that the breed was intended to display. These Appys are what I consider to be a breed, and are what I term "true" Appys. Appys were developed as work horses - not show horses. Other than their color, they were not bred for aesthetics but rather for their ability. As a result, again other than color, they are not the most aesthetic of horses...thick necks, large heads, rangey - almost scraggly actually, and certainly without the "classic" look of an Arab. Their origin is Spanish and they were bred for versatility. They are arguably the most versatile breed there is, with a muscle composition and conformation conducive to both endurance and performance. As I like to say, an Arab will beat them in endurance, and a Quarterhorse will beat them in strength, but if there were an equine decathalon, it would be next to impossible to beat an Appy - as a breed, of course...individual horses will always differ. Most, although not all, of these horses trace back through horses ApHC originally designated with an "F" prefacing their registration number. Because Appys were bred for versatility rather than specialization, most of the old foundation Appys were not raced or shown successfully, so looking for "famous" horses in their pedigree is likely to prove frutal - there are no Man-O Wars in Appy ancestry, simply because of their versatility.
Then there are "foundation" Appys as designated by ApHC's foundation pedigree designation. These can be true foundation Appys, but generally are nothing more than horses that have a certain percentage of Appy blood. The term "foundation" as ApHC uses the term, is meaningless. Remember that ApHC is not a breed registry, and most of the "Appys" ApHC registers are actually mixed breeds, with many having very little Appy blood at all. All the term "foundation" means as used by ApHC, is mostly Appy - as opposed to the "Appies" that are actually mostly Quarterhorse. As a group, these "foundation" Appys are less versatile than true foundation Appys, although they are still more versatile than most pure breeds, and many of them are strong performers in specific disciplines. They display cleaner lines, a more classical look, and are more aesthetic than the true foundation Appys. Most trace through strong modern Appy lines like the Plaudit, Bright Eyes Brother/Mighty Bright, Goer, Wapiti, Joker B, and Colida lines to name a few.
As far as where to get information, I don't know that I can point you to a specific place. There is a little information all over on the foundation type Appys as defined by ApHC - you just have to assimilate it here and there over the years. As far as true foundation Appys, there is really very limited information available. The U.S. Government was kind enough to exterminate much of the original breed because they so outclassed the dull, plodding cavalry horses, so there isn't a lot of information available beyond information that has been handed down orally. We know what they were, what their origins are, what they were bred and used for, and what they looked like, but most of the details that we take for granted in more modern breeds or in breeds that were developed by more organized cultures with more extensive written languages, are missing. We know from information handed down from generatin to generation, that the Indians were selective breeders and are rumored to have been ruthless cullers. But we also know that there are conformation variances in Appys - likely due to their intended use, with both draft and endurance objectives within the same breed, almost as if there are sub-breeds within the Appy breed. So much remains a mystery, and will likely remain so.
Perhaps the best source of information is from long-time foundatin Appy breeders themselves. You will almost always find a comeradery among foundation Appy breeders, and most of them will be glad to share what information and knowledge they have - it will be far more likely you will have trouble shutting them up than getting them to talk about foundation Appys. Understand, that because of a lack of written records during the time Appys were developed, it is difficult, if not impossible, to separate truth from fiction, or determine if what has been handed down orally is myth or fact or embellished fact.
Because ApHC continues to permit outcrossing, Appys as a breed are rapidly giving way to becoming nothing more than a color variation of a Quarterhorse. There is absolutely nothing wrong with Appy crosses - they can make great horses. I raised Araloosas as well as Appys myself. But the Appy as a separate and distinct breed is in danger of extinction. It is only the efforts of foundation Appy breeders that is preserving the breed. I hope you find the prospect of hel;ing to save the breed appealing as you plan for the future - I would have to see the breed disappear altogether such that the term Appaloosa means nothing more than a color/pattern.
As to foundation Appys having more or better color than mixed breed Appys, there is much we still don't know about LP/PATN genetics. At this point I can't tell you that there is any better or different color expectations out of foundation Appys than mixed breed Appys. But we are still learning, and hopefully the pieces of that puzzle will come together in the not too distant future.
Probably not as much help as you would like, but hope it helps some...
Thanks for the info. I knew nothing about Appys, so it was a great read being we just bought a foundation mare. Thanks so much!