I will relay to you my experience with idiopathic SFN. It began in 2014 with a slight loss of balance and this symptom has progressed at a constant rate although I am still able to walk with a cane. My balance has been my indicator of the progression of my disease. Symptoms started about 1 year later with what felt like a folded sock in my shoes. this symptom comes and goes. Then my arms began to feel sunburned and this symptom comes and goes as well but I think this is alleviated by the Desipramine I am taking which is now at 50 mg/da. I thought that this symptom had gone away but slight symptoms have recurred. I am experiencing slight numbness in my toes. About 3 years ago I began feeling sharp stabbing pains in my feet but my doctor prescribed Gabapentin which has almost totally eliminated the sharp pains. I am now taking 900mg/day and it works for me. One year ago I developed post-herpetic neuralgia which has been far more painful than my SFN. It felt like ice picks sticking me around my left front and backside. The remedy for this was more Gabapentin. At 3600 mg/day I has no nerve pain at all from either of my illnesses. At this dose I had side effects of brain fog sometimes difficulty constructing sentences. My neuralgia has subsided greatly and I have reduced my Gabapentin dose to 900mg/da without any side effects. As for your question 1, I have had sunburning come and go but have associated this with lack of exercise. Alcohol consumption can also cause symptoms to become worse. For question 3, the slight numbing in my legs has caused me not to feel hot and cold, I have no pain with hot or cold, I just cant feel it. For question 4, I have no tendonitis or carpal tunnel. I have no information to share on questions 2 and 5. I do have maralgia paresthetica which pain is eliminated by Gabapentin. My doctor said that this was do to rapid weight gain rather than tight clothing. And for me it made sense. When I learned that I had SFN I was terrified and lossed 30lbs (from 180lb to 150lb) due to stress, but as the stress eased I returned to my normal wight quickly which caused the maralgia paresthetica. For me symptoms have increased slowly over the last 7 years. Hope this helps