Customize ajax add to cart extension on Magento

Hello, I purchased an ajax add to cart for my magento 1.9.1 CE edition. Anyway i need some improvements done: 1) Actually the extension doesn\'t support products with required field in option. For product with option, a pop up need to include the dropdown/radio button options. 2) I need to improve the template (see attachment) to include confirmation message, image and name of product, quantity added, optional field selected, cart summary, Continue and Cart button. 3) Inside the confirmation popup, i\'d like to insert + and - button to increase or decrease quantity of the product on cart. These button need to work with ajax and autoupdate cart total and mini cart + advice client when quantity is less than stock availability.