I am Canadian too.
I just had my joined naturalization interview and removing condition interview. All they need is your American ID: Driver license, State ID to verify your identity. She didn't even look at my passport. Though i did left the USA for a week after i submitted my N-400 form, she still didn't look at my passport. I just said that I went to Mexico for a week. They have all travel data in the computer.
Bring your expired Canadian passport. No need to get a new one.