Hi Offroad,
-
You can’t. Only the customer can change their billing address by logging in into their account and changing it themselves via editing their addresses
-
From the order admin, click on the order, then scroll down below and you should see "Order confirmation email was sent to customer name" with a button below it. Clicking on the button will show the email being sent and a button that will allow you to resend the order confirmation email:
Hope this helps and if you have any questions, feel free to ask here or through my contact email below! 
