There are a bewildering array of websites. Here's the scoop on a few of them:
National Parkinson's Foundation, which I already mentioned. They have some interesting forums and a helpline that you can call for info, referrals, etc. http://www.parkinson.org/understanding-parkinsons
Michael J. Fox Foundation https://www.michaeljfox.org/ They are focused on research, though they have good basic information, too. They have information about clinical trials - some of which are surveys or other studies that can be done online. You can search for studies in your area, too.
Parkinson's Disease Foundation http://www.pdf.org/ has a helpline, too. I've called them about support groups. They publish a PD Resource List (free) that is terrific - lots and lots of resources.
Davis Phinney Foundation https://www.davisphinneyfoundation.org/ Founded by a PD patient, it as lots of info and resources
American Parkinson's Disease Association https://www.apdaparkinson.org/ Has state chapters, sometimes with info about support groups, but only tells about some support groups.
See what I mean about lots of websites? Most of them have enewsletters that you can subscribe to. You can also Like most of these on Facebook if you like to get news that way.
You're at a point where things are pretty overwhelming. But start looking for a good PD exercise program - that has done more for me than my meds. If you Google Parkinsons Disease exercise and the name of your state, you can find a lot. I'm partial to https://www.rocksteadyboxing.org/find-a-class/ but there are many good programs.

I found most of the books on pd are too general -better to research specifics on Internet -many interesting studies in UK and Australia - and so many different suggestions -I have been trying to find out more about hypobaric chamber therapy - it has been successful in treating brain issues, cancer, fibro myalgia etc. by infusing oxygen and rejuvenating damaged cells - they say it works for pd in that it does not allow the remaining cells to deteriorate but not enough testing and of course insurance does not cover it -

Rock steady boxing is good but the ultimate purpose is to sweat enough so that you bring oxygenated blood to the brain -this helps stop the destruction of remaining dopamine cells -

The New Parkinson's Disease. Treatment Book by J Eric Ahlskog, PhD, MD is informative.

There are LOTS of books. One is Navigating live with Parkinson's Disease. If you go online, the National Parkinson's Foundation has lots of useful information. http://www.parkinson.org/understanding-parkinsons The books don't have more information about how PD happens, more about treatment and how to cope.