For Dallas Office, please bring your USC spouse with you on the interview day. From your timeline, 99% you will get a combo interview and officers will ask for USC spouse. While waiting on the 2nd floor for my spouse N400, I see Officer asked many applicants if USC was with them and they interview both.
With my spouse join interview(I751, then N400), officer asked my spouse if I was with her, and interview both of us.I751 interview really simple since our case is solid. N400 was the same: standard civil test questions, Yes and No questions on the N400 form, then reading and writing on the tablet. Status changed to oath ceremony will be scheduled 30 mins after we left Dallas field office