AJAX Shopping Cart

Yes, of course. You can choose how the pop-up window should look like by changing colors of its elements. This can be done in System > Configuration > AJAX Cart > Visual Options:

Yes, you can add this option. Please navigate to System > Configuration > AJAX Cart > General Settings and set “Allow to change product quantity in confirmation dialog” to Yes:

No, our extension doesn't work with the up-sells at the moment. However, it's possible to display related products in the ajax window boosts sales, as you offer matching items to a targeted buyer. This will help you to increase the average order value. To enable related products display, please navigate to System > Configuration > AJAX Cart > Selling Options and set “Display Related Products in Confirmation Dialog” to Yes.

Yes, you can choose a preferable variant in System > Configuration > AJAX Cart > General Settings: