Shopping cart integration to Wordpress website with PayPal

We have a Wordpress website that requires a professional shopping cart installation. See [login to view URL] We would like to have the product pages improved with better appeal and the implementation of a well thought out shopping cart that will allow for multiple options to be selected before adding to the cart. We also want to incorporate Fedex shipping rate calculator for those items marked with shipping weight and sales taxes calculated. We would then like to interface with a simple PayPal checkout. We currently have about 25 product items and most are simple select items, some with set shipping fees.