Print quality is good — not exceptional, but quite good in many cases — for the black and white photos. For some of the color photographs, Eggleston's come to mind, it's adequate.
Many of the Robert Adams photographs can be found in his monographs. I haven't seen the Eggleston photos in the books I have, but I have only three. The Papageorge seem to be from his At the Beach series (second LA trip in 1978) recently reissued by Stanley Barker Books. I don't recall seeing the Stephen Shore photos in Uncommon Places (I didn't check, will do later). They might be in American Surfaces or Selected Works 1973-1981, neither of which I have (D'oh!). In an interview with David Campany, Shore stated that there was "close to seven hundred" photos from the Uncommon Places project he "found interesting", meaning he took many more, so these might not appear elsewhere.
The others I can't tell. They might have done some of the photos for this project but re-published them later in a monograph, exhibition catalog or retrospective. I wouldn't be surprised if this were the case for Mary Ellen Mark and Elliot Erwitt, for example, who, as opposed to photographers such as Baltz, have had many books of their works published.
It's a great book to flip through. The quality of imagination and renewal of the photographic eye in what is just a sample of a new generation of photographers (except for some older ones such as Callahan) is pretty amazing. You get a sense that American photography is at a turning point, that it was breaking from (or at least renewing) the various aesthetics that had dominated in the 60s — the photojournalistic approach of the mass movements (the Vietnam war, civil rights, etc.), the post-The Americans-style street/documentary photography (Diane Arbus had died seven years earlier, Garry Winogrand had by them done most of his major works, and others, like Bruce Davidson, were already well-established photographers), or the Ansel Adams/Minor White sphere of influence in landscape photography (which tended to veer into pure abstraction with the latter).
In other words, I can imagine being a young photographer in the late 70s, running into this and being quite exited about what was happening, especially with the photographs of Lewis Baltz and John Gossage, which were unbelievable audacious.