People do use them in Australia for foxes as well as smaller predators but generally speaking livestock guardian dogs are more commonly used for poultry than camelids etc. Camelids are more likely to bond with similar size herbivores than with much smaller birds. They should still do the job as they are bent against predators that threaten their own young, but unlike dogs they may not react to some other threats which can kill the poultry but pose no threat to their own young. So they should chase foxes off but might pay no mind to a raptor or other small predator decimating your flock.
Two is a better bet as they are social and do better in groups. Some of them will guard your animals against you too though, so it would pay to ask the seller if they're okay with humans handling or interacting with their charges.
Some people cannot get into the paddock with their own LGDs either, they will rip even the owner to shreds. They have to lure the dogs/alpacas/whatever away with food and restrain them before they go do the normal caretaking of their flocks like drenching etc. A lot depends on the training the animal has received as well as a few other factors like breeding. Suri are supposed to be just as vulnerable to dogs etc as sheep are, according to some, but others say they will defend. Of course two animals have a better chance than one against one or more foxes or dogs, but some will not even defend your animals. A lot depends on the animal in question. Some will even bully or kill the animals they're supposed to be defending.
Livestock Guardian animals are known to attack their owners sometimes and this can change without warning, for example you may have a llama/whatever which has never shown you aggression, but if one of your animals gets stuck in the fence or whatever and you go to help it and it's carrying on like you're killing it, the LGA may see this as you attacking one of the animals it has bonded to, and hence may attack you in the animal's defense.
It would pay to get one that's already established itself as a proven-reliable flock guardian, needing no training, familiar with and friendly with or at least tolerant of humans.
Best wishes with your search, I'm in the same boat as you there.