What should be the name of the field for autofill to work?
Only insert!
What should be the sort of the insert field?
This should be the first field in the inline section.
Is it good practice to calculate the list directly in the insert?
No. It is recommended to create a technical field in the header h_insert, perform the list calculation in it, and refer to it in the insert:
=: #h_insert
What conditions must the list meet for autofill to work?
This must be a unique list — values in it should not be repeated.