Shopping cart wishlist

hello i Have a couple questions about my online comic shop. snappingturtlecomics.com is my wp/ eCommerce online comic shop but i want to be able to have people create accounts on my site as well as create a wishlist of items there looking for so that when i get it they are notified the moment the item is posted on my site. the other issue im having is my thumbnail pics are hella blurry some times. please take a look at my site and tell me what you would suggest. thank you so much. Im new to this whole web site thing and im learning as fast as i can.