Hi Terri,
According to your 2nd question, I found a pilot released note may help you.
It corrects the following behavior:
************
The user has defined default values for the PO header, e.g. Payment terms or Incoterms as Personal Settings.
When creating a purchase order using e.g. ME21N, the default values will be overwritten by the values from the vendor master record.
************
But as it is pilot released now, you may need to raise a customer incident to get it.
Best regards,
Yang Bai