I am in exactly the same situation. Funded Phd starting this fall, nothing left to do but the F1 visa and a US girlfriend of a few years.
I would be surprised if they recorded what was said as you go through customs as they rarely wrtie/type stuff down. I think the questions are more of a test of your confidence and to see if you contradict yourself. *This is just my opinion so don't take my info as fact*
When is your interview? Could you keep me posted as to what the outcome was and what questions they asked? Any help would be greatly appreciated!