einar,
You ask some interesting and very astute questions. I agree it would be appropriate to see a neuro if you have concerns. Having a tremor does not necessarily indicate a PD diagnosis. Many things can cause tremor.
My primary symptom is tremor on my right side. I was diagnosed in my early 40's, 8 years ago. My first symptoms were clinching and releasing my toes on my right foot - to the point where I developed callouses (sp?) on my toes. I would also bounce my right left a lot. If I consciously stopped my right foot from bouncing, then my hand would shake. I sometimes had trouble with legible handwriting and certainly had smaller handwriting as time progressed.
Although there are some meds that claim to possibly be neuro-protective, there really are no pros to cons about starting meds earlier or later (with some caveats to that statement). When you start meds and how quickly you ramp up on them is a personal choice. Starting early or late on meds is unlikely to have an effect on the significance or progression of PD. If PD symptoms are not bothersome, I would be inclined to wait to take meds. I started right away because my neuro suggested it. In retrospect the dosage was so low that it probably wasn't doing anything. If I knew then what I know now, I probably would have delayed the start of meds. I still am on a low dosage ... especially considering that I have been dx 8 years and have had symptoms 10-11 years.
You raise an interesting question about eligibility for long-term care insurance, etc. It's true that one basically is ineligible if diagnosed with PD. One might consider getting the insurance before a dx, assuming you could cancel it post-dx if PD or other ineliglble dx is not determined.
As you probably have read, everyone progresses at a different rate and responds to meds differently. I hope this helps.
lizzy4451