how do I remove dependency on providing shipping/billing info?

I want to make my store "digital only", so it doesn't ask customers for shipping/billing info during check out or account creation, and only requires name, e-mail, and a password.  I'm pretty sure I can find in the templates where to remove it from the front end, but I'm not so sure about the handler/form back end code.

Can you point me in the right direction?  Thanks!