shoppin cart

I have been testing Download monitor Shop with paypal sandbox. everything works fines, but i have the following problems

1. there is no way to add items to the cart, clicking the purchase button takes it to the cart page, so if we need to add another item to the cart we need to navigate back to the products, also there is no way to display the cart anywhere on the page.

2. when we try to purchase the Items that was purchased earlier or if we had removed items from the cart, cart page returns empty the next time we try to purchase or add the same item to the cart.

Pls let me know if there is any way the feature(1) and the problem(2) can be added and solved respectively.