Mainly, I want a guard dog to deter smaller predators and alert me to bigger ones. Guarding the house itself would be a plus.
Do certain breeds fit this criteria or am I looking for almost any dog that barks?
A terrier would likely be a good choice for small predator and pest control, IF your chickens and rabbits are in secure pens. Consider also the energy and typical noise level of the breed. Terriers are very high energy, even when running around 1/2 an acre. Shelties, as mentioned above, have long coats and are known for being major barkers - perhaps not the best dog to live outdoors with neighbors around.
If you want a typical LGD, there's a Facebook group for finding them called "LGD Locator":
https://www.facebook.com/groups/LGDLocator/
You'll want one that was raised around small livestock.
I know there are guarding breeds that tend to just hang with their charges rather than roaming (like Great Pyrs tend to do), but don't know which they are off hand. But individual personality and a particular breeder's lines can vary wildly from the "norm" for each breed, so I'd cast a wide net, looking at typical behavior for a particular breeder's lines rather than just breed stereotypes. Or get an adult with proven abilities.