To add a new payment method, make sure to complete all fields without any errors and that updated information will be saved to your account. You can choose to make any card your primary (the card that will be charged first) as well as delete any old or no longer needed payment methods.
You can add multiple addresses (such as a separate billing and shipping address) to your account at any time. Make sure to mark the "primary" address as the one that you will have your items shipped to primarily.
If you would like to change the frequency or the type of notifications that you are receiving, choose "notification preferences". From there, you can select the cities and keywords that you would like to be notified of. If you would like, you can also choose to unsubscribe from all notifications.