Here is a good starting point for understanding ADU attributes:

The preferences starting with “ADD” only affect whether to add or update, the matching logic will be unaffected. Also the TA help page specifies that these
“Determine whether uploaded name/address/telephones/email information should be used to make changes to existing records.” The data will be used for creating a new record regardless of how these are set.
However I want to reiterate that some other attributes do affect matching including the ones that start with “Unidentified”.
If do_updates is blank that will be considered the same as N.