Help to complete a WP E-Commerce Site

We have a Wordpress site based on the Getshopped WPEC plugin & gold cart. The site is 90% finished, but 2 items need to be completed: 1. Tax does not seem to calculate at checkout (tried upgrades & default theme but no luck). 2. We would like to add an option at checkout called "Rush Shipping". When checked, the total increases by $30 (taxable). This rush shipping charge should also be reflected on the purchaser's confirmation email and in the admin sales reports. Can provide more details to qualified bidders. We would provide a staging URL, FTP and mySQL info. Thanks