ok thanks for replying. I had a feeling you would use the second USB port for hard drive. Its a good idea and allows for in keyboard backup of data. But your users should be aware that it is only suitable for data and of no use in case of primary hard disk faliure. (unless you have made a quick access panel that allows for fast swapping of the drives)

points 3 and 4, thats fine; you only needed answer one of the as question 4 is not so important after answering question 3. Again as long as the customers know that you are taking responsibility for the warranty and support thats fine. In the UK we tend to look after customers long after the warranty period, but obviously will have to pass that over to you if they apply your product.