Glad that you are thinking about things.
Not only did your girl have elbow dysplasia, but to have died that young with cancer would also make me not even think of getting a dog from that kennel.
If they are only selling the pups at 4 months of age...and keeping them together and not really socializing them....that is awful too. It would be really hard to house train a 4 month old pup that has been allowed to poop and pee in a kennel area also.
I would stay away from any place or anybody that is making their living selling dogs...these are puppy farmers. Also you say they have many other breeds there? That to me sounds like a clean mill. It's a puppy mill, but the surroundings are clean.
Having no titles also is bad. How would these puppy farmers know that their breeding stock is breed worthy??
As you know Rottweilers have way more problems then just hips...passing OFA hips scores does not make a Rottweiler breed worthy.
Keep looking for a good COE breeder....it will be worth it. Try hanging out and some dog shows...not only AKC but some of the German style Sieger shows. There should be many good dogs at these shows, that have good owners and breeders.
Gina