Hi Glen,
Generally speaking, you have identified 2 issues as part of configuring Purchase Orders. But you need to know exactly what you are talking about because your choices have a big difference on how well your PO processing can happen.
There is a reference cost that you can define that will display when you create a PO, and a default cost that you can use that will default as the unit PO cost when you make a PO for an particular item. And you get to determine which "cost" you choose from Recent Cost, Standard Cost, Cost1, and Cost2 fields for which cost field gets mapped to these2 options. And you could keep the default and reference cost the same field (and cost) if you want.
But it gets more fun.
For each cost field type, you get to determine whether the cost being reported is just the actual cost from your vendor's price list (and normally that would be the default), or does the cost include miscellaneous charges for a calculated landed cost, or do you want the cost to be in the currency of the cost from your supplier's price list, and if the item goes into negative, what cost will you use for the Order Entry End of day processing for the invoice.
Normally, you use the landed cost including allocated misc charges and currency exchange as the recent cost so that you get the best option for the invoicing of items. That also affects and gives you better margin calculations, and so you set your recent cost to be a loaded landed cost and would not be a default cost but could be a reference cost (when creating the PO). Basically, you set your recent cost to be your best cost for adding the costs to inventory, so that whether your item has quantity available to ship or goes into negative, you generally get the same cost calculation for cost of sales. You might use it as a reference cost but rarely would you consider using this calculated "recent cost" as the default cost for a Purchase order item.
Normally, you would use either Cost 1, or Cost 2 and (rename as Vendor Cost), and this would be the cost in the vendor's currency that matches to the vendor's price list. And so this would be the cost that would be the default cost for your POs, and would not include any additional misc charge allocations.
Standard cost is available as a cost field but we rarely see used unless it referenced with a specific cost that is imported from a spreadsheet with a defined purpose in mind. But rarely used to be populated by anything from Purchase Orders, in our experience.
This is how we would configure and we have set and configured more than 100 PO modules in Adagio systems.
Best,
Brian