We will never resell or give out your information. We will also only respectfully email when we feel its non-intrusive, password resets, timely emails. Nothing excessive unless you ask for us to update you daily with the comics you follow.
You do not NEED a username, but it will be required if you are planning to make any edits to the data on inkoutbreak, or to take part in "social" aspects of the site.
Postal codes are used to give us a vague, guess at where you are. So moving forward we can use that info to suggest things to you. Again we respect your data, and we will not release this information unless you say its ok.
Feel free to email Brian King at bking (at) inkoutbreak.com or ask a question on twitter ( @inkoutbreak ). Remember there is no such thing as a dumb question.