Our rotty is very sweet and nice, BUT she does protect her property if she is in her kennel and a stranger comes in the back yard, she will bark and sound mean- she is letting that person know they are in her "packs" territory... but if I let her out of her kennel she will run to the person and lay down to get a belly rub.
Seems like when they are confined they are protective, so chances are these dogs are letting you know that you are by their territory.
BUT... since you and your kids have a fear of them, and you have told your neighbors that you are afraid they should do something- maybe put a privacy fence by their chain link fence so the dogs can't see out.
Also- their continous barking could be considered a noise problem and the police could be called.
I don't agree with keeping the dogs out in such a small place for so long...
I also wanted to say, that I doubt any of my neighbors have seen me take my dogs to the vet- but just because they don't see me doesn't mean I don't (I now own half the place - lol) so I wouldn't jump to the conclusion that they don't go to the vet, just because you don't see them.
Of course my neighbors do see us go for walks, because they all smile when they see us walking our big rotty, and two small yorkies...