Example - US-Tax Configuration

I am dealing with an Oracle customer that had Oracle back to 11.0.3.  They have upgraded through time and are 12.1.3. They had processes in place where they handled Use tax - the populated the tax code on the PO and that would flow to AP.  Now with 12.1.3 - they have a new operating unit - so we need to configure eTax similar to an existing operating unit - but unsure of what has to be defined for an operating and what does not.

For example - they need First Party for new operating unit assigned / added as a party in E-Tax - the other operating units have a PARTY TYPE =