I dont work with dragons much so I am not the best person to answer this qustion, but heres what I have experenced with astral dragons.
Dragons, as a spirit on the astral plane of existance, tend to be on more of the powerfull side compared to other spirits. Not the top dogs, but up there. With that said, like anything else it depends on the individual dragon. Some humans can run fast, while others are good at math.
They can communicate with people on the physical plane, just as any spirit can aslong as the physical person has a open 3rd eye. Most interaction would take place on the astral side as dragons are spirits and are not physical. However there are some people who believe that a small amount of physical dragons do exist, are extremely powerfull, and avoid any connetact with humans.