how to edit the page template for product/cart and other store pages

I am setting up a marketpress store and see the “store front” page under my pages section of my wp admin. I can change that store template by clicking the template drop down and selecting one of my many page templates. Problem is that I don’t see this option for all of the other pages (i.e. cart, products page, etc). Where can I edit these pages? These pages are not showing up in my pages section of the backend of my wp.

Also, my marketpress store is not playing too nice with my current theme. Would I have to edit each file (product page, cart, etc) individually? Or can I create a template for the store and use that for all of the individual pages? Is there a quick fix? I do not want to install another theme as I want to use the current one I have for my website. I want this store to integrate with my current theme.

You can view my current store by visiting the following link:

http://othelsart.com/art-store/

Thanks in advance!