InfoPass Appointment tomorrow

[NLP 0]

Two weeks ago tomorrow we got the oh so pleasent notification that our mail from USCIS was returned as undeliverable. Quite the day ruiner as we are really on a time crunch for the AP. However, the email was referring to the I485 and the EAD. I suspect it was a mailing to notify us of my wife's Biometrics appointment, but it could have been an RFE. Anyway, she called CS number while I set up the InfoPass appointment, knowing we'd have to go in person based on what I've read here.

However, I'm not sure what I'm walking in to tomorrow. We indeed verified our address with CS over the phone, made the appointment, and talked to our mail carrier (so has it our box was properly identified and changes of address were completed BEFORE we mailed the AOS packet, but since it was done online our carrier stated she "never received our case").

My question is what should we attempt to do at this appointment and what documentation, if any, should we bring? Also, will it be fair game for me to talk about our dearly needed AP?

Thanks in advance.