1. You can upload the tax transcripts for good measure, a lot of people do and I would recommend it.
2. They will use the same photo you took with the original biometrics. I believe it’s the photo on your current Green Card (although not 100% sure so don’t quote me on this)
3. I would not request an alternate oath. Usually you have to have an emergency or valid reason to reschedule any USCIS event, Oath included. I know a woman who was unable to attend the oath because she was heavily pregnant, and she must have waited around 7-8months to get a rescheduled date.. if you ask to be rescheduled, your case goes to the back of the list again.