The order attributes page is a list of all the information that gets pulled in or affects an order. What you are looking at was all internally generated by eCommerce on install. There is really not much to do here. You do not want to delete any of this or it may break eCommerce.
What you can do at the Order Attributes field is add extra information to the bottom of Billing page to ask your customers any last minute information. Even though it is not listed here, your customers are asked their email address by default.
Here is an example of how to set this up:
Here are the settings for a text field asking for alternate choices. Any new options added to the Billing set of Order Attributes will be added to the bottom of the form that asks customers for their billing address. You can also make these attributes required.