I need to add additional fields in the customer's information form during checkout, such as Telephone number and "How did you hear about us?". I don't see within the Commerce pull-downs in the Admin panel any way to do that similar to how fields are added in other Drupal forms. I assume Commerce allows such customization. Of course that data needs to be added into the database records as well.
In addition, how are those additional fields added to the email that is generated when the order is completed? While the customer may not need it, other people within the ordering / fulfillment process are designated as getting copies of that email and need that information within the email.