Yes, but not just Golden Retrievers et Cancer
No they are very common
Not sure what exactly you are asking, but this is not a common ailment in Staffies. Hip dysplasia is more common though.
They are "Retrievers" and in the "Hunting" Family.
It's not technically "law" but it is absolutely necessary! i.e. The Kennel Club won't register the breeder's puppies if they can't prove that the parents have been hip scored. This is to prevent people breeding poor quality dogs which are even more susceptible to hip dysplasia. (You're probably aware that this is an all too common ailment in Golden Retrievers)
Intelligent and popular dogs with long hair.
Yes. My dog developed a cyst on his back later in life. When I took him in to the vet I was told that cysts are very common in both golden retrievers and labs, my dog is a mix of both.
Desirable traits of a goldendoodle include being friendly, intelligent, and low-shedding. Undesirable traits may include potential health issues common to both poodles and golden retrievers like hip dysplasia, as well as a high grooming maintenance due to their curly coats.
Labrador retrievers, Golden retrievers, German Shepherds, and poodles. Doodles (goldendoodles, labradoodles, etc.) are also becoming more common.
A common nose ailment is a deviated septum.
Common ailments are diseases or other health problems that lots of people get; the cold is perhaps the most common ailment, arthritis is a common ailment, obesity is a common ailment.
The most common ailment among any humans is the common cold.