I think "merchandise" would be a better name than "shop".
The front page picture should tell the visitor what he can buy at the shop. The "now open" is unnecessary information.
Instead of a big "New Designs" banner (where you cant see the designs because of the text on top of it), just add a little "NEW" label to the t-shirts.
The shop navigation should be on all shop pages, so a visitor can always return to the shop main page.
It's hard to find the price, and some users will not understand how to choose the right t-shirt size. It's the most important information, so it should be in the middle of the page, and bolder!
Also: Comments in a T-Shirt shop?
Take a look at
http://uxdesign.smashingmagazine.com/smashingmagazine published many articles about UX Design, the checkout process etc.
