Just take copy of 485 recepts, passport and two immigration style photo. Download the I-131 travel document from INS website and complete it.
You may not be needed to pay again if you give AP receipt number.
No need to show any urgency and emergency to INS, just you need to say that you are going for personal reason.
Make sure to call INS to cheeck if your local INS office process the AP application. My local INS office is Baltimore,MD.