A broad spectrum of the more common antioxidants will improve general health, but will not significantly extend lifespan or slow the basic aging process. A major reason for this is that many antioxidants do not penetrate into the cell's mitochondria. The mitochondria are the primary energy-producing components of the cell. The mitochondria have their own antioxidant system. This is why a good antioxidant supplement will contain a trace amount of manganese.
Vitamin E has no apparent toxicity, even in very large doses.
Vitamin E, itself, will not have any significant adverse effects on blood clotting. However, a breakdown product of vitamin E, called vitamin E quinone, does substantially inhibit blood clotting. The rate of conversion of vitamin E to vitamin E quinone varies greatly from person to person. In a few individuals, several hundred I.U of vitamin E may cause serious problems with normal clotting. To cut through the nonsense about vitamin and mineral supplements that comes from conventional physicians and the popular media, read the review articles on the subject in legitimate medical journals.