What is the ruling on using olive oil imported from Italy that is not labeled "halal," given the unavailability of an alternative, and is it possible that pork fat has been added to it? And what is the ruling on pasta imported from Spain?

The basic ruling for the aforementioned oil and pasta is permissibility. Their use is not forbidden unless one is certain or has a strong presumption that they have been mixed with impure or unlawful substances. Mere doubt does not render food unlawful.