Where could I find Transaction Templates for CSV uploads (ex. Purchase Orders)? Is there a place inside or outside Netsuite where I can find some templates and mandatory fields?

I usually recommend looking at the UI for identifying mandatory fields. You might be able to access the templates in the File Cabinet from your implementation team. If not, you can use the UI to identify the header and line level fields. If you are importing multiple lines, the header level fields must all be the same for each line. I hope that helps!

go to the forms and grab all body/header and line level fields from there; you can also see there which fields are mandatory

Thank you all.

@mescalante don't forget about us at CloudExtend? Hope you are well my friend.