BCG definitely does have some side effects. Its purpose is to stimulate the immune system so that the bladder lining will reject cancer cells. The side effects are due to this action. Fatigue, urgency, bleeding for example are all side effects that can/do occur with BCG and they do increase as the number of treatments increases. These side effects are bearable (and if they are not, even with reduced dosage, BCG can be discontinued....the doses already given are effective!) and are certainly much less than with other types of cancer where traditional chemotherapy is indicated. Several times my treatments had to be postponed due to irritation (BCG-induced cystitis). But I am so glad that I did finish them.
No, once I had healed from all the treatments life became normal again.
As for "other things" I believe that it is never a bad idea to have a healthy diet! BUT whatever caused the cells in the bladder lining to become "unstable" and become cancerous probably happened many years ago. Suddenly using trendy supplements or faddy diets will, IMHO, have no effect on anything except your wallet! Hydration by drinking a normal, not excessive, amount of water and other fluids is a good idea of course.
Hope this helps
Sara Anne