Hi,
1. When I try an order on your website, I get the error:
Some required information is missing or incorrect. Please correct the fields below and try again.
Error: PayPal Express Checkout is not setup on this account.
That error means that your PayPal account is not a PayPal Advanced account. Please contact PayPal support for help on that.
2. This means that your taxes are not setup properly. We would need a screenshot of your taxes listing, and a screenshot of your product edition page on the backend.
PS: Please try to create different threads for different questions in the future.