Hi Mat52
Sorry to hear of the trials you're going through. Just a couple of quick suggestions (my computer's on a 'go slow' today so getting anything done is a hassle).
Firstly - did your RA originally start as a result of some other illness? eg my family has a strong tendency towards autoimmune; my father developed RA after getting Leptosporosis, my brother got RA after a bad bout of pneumonia. Could there be some other underlying undiagnosed condition that is contributing to this?

Re your Neuro review appt. Focus on what is important to you - both in imparting info to the doctor and getting your questions answered. Sometimes they don't want to commit themselves to specific treatment choices - especially if your symptoms are in remission on the day of your appt. Try asking them if it would be possible to get an urgent appt. during the middle of a flare. Also see if the nephrologist can forward a report to the neurologist before your appt. Her input could be important.

Is the pain in your mouth definitely TMD or could it be Trigeminal Neuralgia? - I've got both - fortunately both under control at present. It's good you're seeing the Maxillo Facial specialist as this is how I got my TMD sorted. They made a custom fitted jaw splint and gave me facial exercises to do - these have definitely helped and I feel are a better option than the $5000 surgery proposed by an orthodontist. TMD can be due to both a physical cause (changes to the jaw from RA are possible) and a psychological process -all the stress you've been through could be adding to it.
Hope this helps - please feel free to ask more questions.