When a customer redeems a gift card, the checkout displays one of the following options:
If the balance available on the gift card is greater than or equal to the order total, then the customer can click Complete order.
If the balance available on the gift card is less than the order total, then the customer is prompted to choose a second payment method for the balance before placing the order.
Yes, provided there is still a balance remaining on the card.
Yes. A customer can redeem another gift card during checkout.
No, you can't use a gift card to buy another gift card.
Yes, gift cards are applied to the final order total which includes shipping and taxes.