How Project Costing handle Exchange Rate in PO --> GRN --> Invoice --> Payment against Project Budge

Dear Experts,

I would like to consult you all about How Project Costing handle Exchange Rate in PO (Encumbrance) --> GRN (Actual) --> Invoice --> Payment against Project Budget?

Scenario1

1. Purchase Order

2. Goods Receive Note (GRN) cross years, then:-

2.1 Exchange rate may more than PO, questions:-

-system use existing Project Budget in GRN period?

-How is PO Outstanding Amount?

2.2 Exchange rate may less than PO, questions: will the system returned different amount (from exchange rate) to Project?

2.3 Is there Project fund checking on GRN process?

3. Invoice
3.1 Is there Project fund checking on Invoice Validation?
3.2 Is there Project fund checking on Concurrent "PRC: Interface Supplier Costs"?