150846 X-Cart Payment Address Mod

We're getting far too many fraudulent orders. We need a modification to insure that if payment method is credit card, billing address must match shipping address. Shopping cart is X-Cart. For other payment methods alternate shipping addresses are allowed. Will need an error page stating that "the shipping address must match the address on file with your credit card issuer etc. etc...." with a "retry" button to bounce back to an (or the) 'enter shipping address' page without disturbing the checkout in progress cart totals and values. This should be noted when users create their profile as well that the shipping billing must match the credit card billing address if paying by credit card. I believe this should be quite simple for the more php / js experienced than I. (i.e. if payment method = (credit card) & (billing address) ne (shipping address) then (our new error page) else I would also like to revise the checkout page to make it more streamlined and user friendly (see attachment). The current user information fields page would be displayed only for new customers - existing customers could simply login or retrieve their account info if necessary. I would like to add a newsletter subscription link to this page as well (again, see attachment.)