My wife and I are the same. Both have two separate cards, once for initial two doses and one for the two boosters.
We will be going tomorrow to our family doctor's office and getting the flu shot and seeing if we need to get the newer vaccine.
The little wallets that hold our passports on one side and shot cards on the other is very convenient.
Yes, to fully complete the check-in online all that information is needed.
However, as mentioned earlier, you can go to check-in section of the app, select a check-in time and exit. Then at your leisure you can go back and upload photographs, passport information, etc.
It does not all have to be done when you first use the check-in on the app.