515601 Shopping Cart Fix and Additions

Hello, I need a quick fix (for the right person) on my shopping cart. For some reason when customer chooses my [login to view URL] checkout it gives an error message now. It was working before when I first set up and tested it. (The site is newly launched - no sales) I also want to make the checkout look better and have more functions to it. A prime example of how I would like it to look is on this site: [login to view URL] It needs to be different though, but with the same idea and look(ish) I also have a category that is not in my Advanced Attributes and I don't know how to get it in there. I'm sure this will be easy to do, I just don't know how. Thank You For Time And Consideration. ~K