You haven't gotten anywhere approaching this problem from the ED and hand color angle so I would definitely come at it from the fluid intake issue. Personally, I would hold off on the vascular surgeon until your fluid problem is resolved.
I think if you were to explain to the urologist and / or the kidney specialist how you feel better when you drink less and how you feel significantly worse when you up your fluid intake they would explore the issue of overhydration with you. I don't know what tests they might conduct that they haven't already but since your doctors, so far, have not been made aware of these symptoms they may have misinterpreted some results or not ordered certain tests because they were deemed unnecessary.
If you're NOT dealing with an HMO, getting a referral to the kidney guy should be pretty easy. Ask your urologist or your GP. Chances are good that the urologist will refer you out since he can't really find anything wrong with you to treat. If there are any pre-requisites to see him or her that will depend a lot on the doctor. I don't think there are any hard and fast rules. They're all very happy to take your money.
i don't think you'll have any problems given your symptoms.
Let your doctor know why you didn't mention these symptoms earlier if he seems skeptical in the least.
Hypothetically, there is always a chance that something is wrong with a body part despite negative test results. A lot depends on how good a particular test is at detecting a particular problem and if it was administered correctly.
Sometimes when tests don't confirm a diagnosis a physician will use common sense and go by the symptoms his patient is experiencing. It's like the old saying if it walks like a duck, sounds like a duck and looks like a duck, chances are it's a duck.
My girlfriend can be quite formidable and she definitely isn't shy about letting anyone know exactly what she thinks.
Lately she's had a lot of problems with doctors so she would be more then happy to put in her two cents worth.
As far as the bloodshot eyes I would mention it to the docs just so they have all the information. It could be yet another clue for them to confirm a diagnosis.
I'm not 100% clear on the posting rules here either when it comes to starting a new thread when you have a big long one going already. You might want to start one with Overhydration. If there are others suffering from the condition that would definitely get their attention. Probably be best to post it in the kidney forum.
Take care and as always keep us posted. I'm very optimistic that you will get to the bottom of all of this.