Custom eCommerce Site OpenCart Preferred

I need a site that is similar to this one: [login to view URL] I need to use an open source cart, preferably OpenCart or something similar that has shipping and tax capabilities similar to OpenCart, produces reports and tracks inventory. I like most of what OpenCart offers but I am amenable to a better solution if one is available. I would like to have options that include not only black & white and sepia, but also color that they would choose before they spell their word and have the option to change at any time. I would like them to be able to change this option for individual letters under each letter, or the whole word under those options. I would also like people to be able to spell the word they want to buy under the header, and the most popular letters dropped into boxes at the bottom of the screen less the options below the word. The number of boxes would obviously need to correspond to the length of the word, with a maximum of say 7 letters on one screen and the scroll feature used on the example site above. The links on the left would be hidden while people are designing words to optimize size of the photos and allow the In other words, if they want to spell "website" then the most popular "w" automatically populates the first box, the most popular "e" populates the second box and so forth. Once the letters are there I would like people to be able to click on the letter and have an option to change that particular letter to another variation of the same letter via a window (with a fade in, fade out effect) that opens centered above the word with all the variations of that particular letter. I would like the window to contain up to 16 letters, but have an option to click a button that will scroll to a new screen in the same window in the event that there are more than 16 variations of that particular letter. In other words, if there are 36 "a's" the initial 16 a's would show in the window and there would be a button at the bottom of the widow to "show more a's" that when clicked would open the window with the next 16 a's that contains buttons at the bottom of the window to view more a's or go back to the previous screen. The number of screens needs to be contingent on the number of photos entered into the database for that particular letter. There also needs to be an option to keep the original letter that populates the box on all screens centered at the bottom. The button to view more a's should obviously only appear if there are indeed more a's to view. The button to go back should only appear when it is appropriate as well. When their word is spelled the way they like it I need them to be able to place that word in a shopping cart for purchase and continue shopping or check out. I also need them to be able to frame the letters with a choice between framing the letters individually or the whole word with different frames chosen at any time during the shopping process. In other words, if they decide they want "frame a" to surround the whole word they could change that option to be "frame c" to wrap individual letters and that will update the view to reflect the change. We will have up to 20 different frames to choose from, shown 4 at a time and I would like those to be chosen by clicking the appropriate frame and selecting "frame whole word" or "frame individual letter" below the frame. The frames need to be centered according to the actual number of frames above the word that is spelled in much the same way as the letter choices, but they can be present any time the letter choices are not being utilized. I also need a "join our mailing list" function, a contact form with captcha, a payment page with a PayPal option and pay with credit card option. I will provide the 350 initial photos of the letters and characters to be used. It is important that my client can add letters or frames and change prices with MINIMAL technical experience at any time.