Change Shopp to Woocommerce in existing website

My wordpress website khattbooks.com runs into all kind of problems because the Shopp plugin is no longer supported. I want to replace this plugin by Woocommerce, but I do not want to change the look and feel of the current website. You can look for yourself all the current functionalities of the website. The must remain the same with one extra: surcharge for payments through Paypal