Magento Site - Fix issues

Work to be done on Website 1. Thoroughly check for all errors on the website like any Javascript, ajax etc.. related error. 2. Some of the known errors includes : a. Ajax add to cart – on refresh product disappears b. Paypal – unable to checkout when currency is in INR or even if it is changed to USD from the top c. Product page – related products add to cart not working d. Ajax functions very slowly during add to cart, wishlist etc.. 4. Payment Checkout through PayU – automated status change on either payment failed or passed 5. Loyalty programme inclusion and Gift Card addition 6. Checkout page is very slow and buggy. Needs to become very fast and responsive as many customers have complained about it. 7. Homepage needs to be modified a bit to make it look more professional and complete. Need to add more content like New / Featured / Sale products (random display). Basically make it more professionally looking. 8. Basically entire website needs to be well polished and all errors removed. It needs to be made fast and responsive thereby making it easy for customers to navigate. 9. Upgrade to latest version of theme and Magento, if available 10. Hence, all the errors have to be resolved thereby make the site fast loading, error free and easy ui for customer.