All I know is that you should be carefull when you use a product that claims to lighten your skin... It could be harmfull to your skin. If you really think its a problem go see a dermatologist. They are the experts and can tell you better than we can.
As for vitamin A... I have no idea. But there are some who believe that vitamin C lightens the skin, though studies have shown it has no effect on the production of melanin and only makes the skin clearer not lighter.
The best way is to lighten your skin's weight instead of its color. In other words, when you discover how beautiful your natural skin color is, it won't weigh so heavily on you any more.
Vitamin E is good for the skin. It also has antioxidants.
Not that I know of, but lemon juice definitely will :)
I don't think it helps in skin whitening. =)
try those lightening soaps:)