You hand the declaration form in at the airport both in your country of departure and in Thailand but you don’t need them to be uploaded for either visa or for CoE
they can’t guarantee the next day service at the minute due to lab being too busy but they still guarantee the next one so still in time for the 72 hpurs
Don’t see why as on the actual Coe it doesn’t say anything about what insurance you have etc so my advice would be don’t upload it, if they’ve already accepted it then just do your flight etc