Something that hasn't been mentioned, in response to the initial question, is that being tired and sweating are a natural part of exercise. Cycling is, after all, exercise. Adding to your base miles and building that physical foundation coupled with proper bike fit will make the distances easier. As to nutrition, cutting back on sweets and excessive fat will help. I don't too much about lighting as I rarely ride after dark. I do know, however, that the old bottle dynamos are relatively inefficient as far as dynamos go.