Ryn asks, "What should professionals know about disability?" (In my answer, I am discussing mostly medical professionals and others who have PWDs as a major part of their work load.)
They should know that disability is just a facet of a person, and makes the person who has it no less of a person. They see so many of us, you think this would become obvious that we are each an individual. It seems a given they would notice that we have a range of other characteristics and experiences that, combined with our impairments, make up our life as a whole.
And yet, in my experience this isn't generally the case. I've gotten to meet a number of new acquaintances and spend time with old friends in these last three years. The wheelchair throws them off their game, with few exceptions, but most pull through to be normal by the end of the conversation. They minority still can't look at me straight at the end, struggles with what to say, feels akward, projects akward, patronizes, remarks on everything I do as a miracle, or ignores my participation in the conversation entirely. Sadly, most of the latter group is comprised of doctors, nurses, "disability advocates" and others that should be the ones to know better.
Instead, they've been taught in their professional lives to think of us as patients, service users, or worse, people they have authority over in some way. Sometimes they get stuck thinking of us as something to be fixed, and not someone to become acquainted with. Too many times, they can't break the mold outside work, and to talk to most of them at work is an exercise in frustration.
What about other professionals?
Too many assume us to be incompetent, and too few take no time to find out what we can do and how we want to do it. If they only knew that communication is the best customer service, I think we'd do fine.
I would like to take the time to praise on profession: flight attendants. Flight attendants are some of the best trained professionals I've ever dealt with as a disabled person. They're attentive, but they stay out of your way. When you do ask for help, most immediately ask back "How can I best help you?"