Questions about Bible Interpretation

I have been involved in a friendly, and hopefully fruitful, discussion over at Green Baggins regarding Bible interpretation.  I have been encouraged to post here some of my comments there.  Because I am excerpting from a conversation, I will have to do so in the form of questions and answers.  The questions cited here may not always be actual ones from there, but attempt to sum up the path of the conversation.

First Question: Isn't the Bible itself insufficient for developing a method of Bible interpretation?  Don't we need to engage in critical studies, to include significant input from outside the Bible?