I have a question? Can Parrots/Macaws and Toucans get along with other bird species in captivity? And are there any example exhibits?
They can, yes and there are many examples. Just to give examples that I saw recently at Antwerp Zoo for toucans there was a mix with Guira Cuckoo, Grey-winged Trumpeter, Red-billed Toucan, Northern Cardinal. Or if you meant some of the smaller Toucans like Aracaris and Toucanets then there are also lots of examples such as in Weltvogelpark Walsrode where many species are kept in the pheasantry mixed with other things. And for parrots, there are also a lot of examples. Again to chose something I saw recently in Antwerp Zoo was Yellow-knobbed Curassow with Mexican Military Macaw and with the smaller species, they are often mixed and an example of that would be the walkthrough tropical house at Wingham Wildlife Park (UK) where the list of free-flying species is Yellow-backed Chattering Lories, Zebra Finches, Australian Rainbow Lorikeets, Dusky Lories, White-cheeked Turacos, Speckled Mousebirds, Bengalese Finches, Goldie's Lorikeets, Java Sparrows, Western Crowned Pigeons, Eclectus Parrots, Black-winged Lories, Green Turacos, Diamond Doves and several butterfly species. As you can see there are quite a few parrot species there.
What about Macaws? And what other species eat hatchlings? Also, is there any way that Macaws, Toucans, and Hornbills can share a exhibit with other birds, if you raise the hatchlings in another location away from them?
I've heard of/ seen exhibits which mix macaws with other species of birds, these are generally larger species, such as fowls, Ibis, other macaws and larger parrots (cockatoos, amazons, smaller macaws). And also exhibits which again include various birds (usually larger species) with hornbills. I can't help with toucans, sorry.
Did you actually read this thread? I don't know how much risk there is with the mixes, but they do exist. There are also examples with Hornbills too (a lot more than with Toucans I suspect), I'm happy to provide examples if you want them.
Many I believe (presuming you don't mean herons and cranes as a mix), I have also seen one(s?) with cranes and herons in an aviary with lots of other birds; I personally wouldn't mix larger herons and cranes with small birds, but larger ones with herons and cranes should be fine.
Also, the Queens zoo in Queens, NY, has a huge dome aviary where in the spring and summer 3 species of Macaw and a few of parrots are kept with each other and other native songbirds. It's quite a sight.
Hornbill Mixed Exhibit examples: lots of examples with various pheasants (peacock pheasants, silver pheasants etc.) such as with Trumpeter Hornbill (Antwerp). I've also seen Tarictic hornbill + Kagu (Walsrode) and other mixes with small hornbills such as Red-billed Hornbill with Bald Ibis, Crested Guineafowl etc. at Artis, though I don't know of combinations including the very large hornbill species. With Herons, there are many example including small heron species such as Black-crowned Night Herons, Pond Herons, Boat-billed Herons etc. with species including penguins, terns, waterfowl, waders, gulls etc. and I have seen cranes with various duck species.
Large parrots, especially macaws, can be very aggressive. They cannot be mixed in small aviaries, although can work with larger birds in very large, multi-species aviaries. Problem is that parrots easily cut the mesh of an aviary sufficient to hold most birds. Large toucans and hornbills are nest robbers and catch and kill smaller birds. Large hornbills are also very aggressive in the breeding season. Again, they can be mixed only in large aviaries with birds of about the same size, and successful breeding of other birds is doubtful. Small parakeets, aracaris and Tockus hornbills are more tolerant, but still the same problems with aggression and nest robbing in the smaller scale eg. towards songbirds. Herons are also avid predators of small birds, although can work in large aviaries with similar sized or very aggressive species. Cranes, like hornbills, are territorial in breeding season, and can hunt smaller birds and ducks as food for their chicks. Less aggressive species are mixable only in very large aviaries, and successful breeding is doubtful. Breeding species like Red-crowned Crane can kill anything which cannot escape to deep water or tree top.
In Burgers' Zoo hornbills flew in the Bush along with loads of smaller species, inclusive really small songbirds and lizards. I heard it became a problem when the hornbills started to breed themselves and needed protein for their offspring. Then, the smaller birds and lizards started to disappear...