Hey Joyce--My advice: please don't stress. Bentley will be whatever size he will be. And he will get trained and get better as he gets older. He is only 5 months old. Try to be patient.
As far as size goes, as you know, Max is a big boy. His father was tall, probably at least 28 inches and was incredibly sweet. Max's mother was on the small side. He is from a BYB. Like you, I had never heard of clearances or breed standards until I joined the forum.
When we got him, we thought maybe 100 pounds at maturity. Max is around 150 pounds now and 29+ inches tall.
That is 25% taller than the AKC standard and twice as heavy. He has been losing weight. But he is "big boned" and has huge muscle mass. We are concerned because generally the "giant" breeds live shorter lives than the smaller breeds. There is nothing that can be done about that now other than control his diet. We do know that he has the bone structure and muscles to support his size.
From reading this forum, I have learned that there are plenty of Goldens smaller than the standard, and also some bigger. They are all Goldens, however, and the most important trait is not size, but temperament. The way you describe "Broadway Bentley" I think you have a puppy with a great, Golden Retriever, personality. Work with him and after maybe a few bumps in the road, you will have a great dog.
As far as health issues in general, our last Golden, Chewy, was a pet store dog. She lived to be 14 1/2 and never had a sick vet visit. Our Golden before Chewy, Golda, also was healthy and lived to be 12+. We adopted her from an acquaintance and never knew her background. Any dog, even one with the finest pedigree, can have health issues.