I have not found any good research the supports the use of moisturizers helping to reduce the appearance of or prevent the occurrence of stretch mark. Making sure you get your fat soluble vitamins (Vit. E and A, etc.) would be good as it would but your skin in the most optimal condition. Using a moisturizer cant really hurt, but don’t bath you body in it as to much can impair skin integrity.
Stretch marks, from what I have read, can fade over time. They might not go away completely but the appearance of some might diminish. The only proven method to really get rid of it seems to be plastic surgery such as laser or a chemical peel, but I am not sure how effective these methods are.