Here are my responses:
1) Yes, I always feel you should expect they will examine everything given they usually do
2) 2020 before its filed is weird
3) Some agents like to surprise, others didn’t think of it during the call, and some are told afterward by their supervisor to add it.
4) You should get a 2848 from them
5) They need to send an audit notice for those and unless you have a 2848 on file they wont send it to you but to the taxpayers directly
6) Gather invoices/receipts from vendors if you can, reconstruct the rest
7) I am not a quickbooks expert so I will defer to the group but they want the electronic back-up so they can see the adjusting entries and audit trail. Key is to not give them more info than that covered by the audit period