You will still be able to review your order before final payment.
CVC / CVV codes are unique 3 or 4 digits on a credit card that helps ascertain that the person using the card actually has possession of the card. Simply put, we ask for this code to help battle fraud.
Visa + Mastercard: use the 3 digits on the back of the card
American Express: use the 4 digits on the front of the card