Re Niacin. Could try niacinimide. Seems to be better tolerated by those in heavy metal groups. Cutler explains-- noamalgam.com
Re Vertical nail lines. I have them too and have some of your symptoms. Some think low iron might be involved. Iron is involved in converting tyrosine into the catecholamine neurotransmitters, the lack of them is associated with ADD and cat. depression--lethargy, poor motivation, etc. Andy Cutler indicates that many people who have a heavy metal problem also have low iron; however he does not recommend high or high-norm iron either!
This is interesting on cancer. He used Cutler chelation, special diets to starve cancer cells, high pH diet, liposomal C, etc. http://www.pdazzler.com/cancers-cure