Pula Airport is located about 5 km from the city center. It is not difficult to get here, despite the fact that there is no regular bus service. You can leave here either by transfer bus or by cab. Unfortunately, there are no transport connections to other cities at Pula Airport.
The distance between Pula Airport and Porec is about 60 km. The transfer is usually organized by hotels and costs about 200 HRK.
The easiest way to get there is to take a cab - there are even spacious minibuses carrying up to 16 people. If you order a cab locally, the trip will cost 500-600 HRK.
You can also take a cab to the bus station Pula (costs about 100 HRK), and there take a bus to Porec (ticket costs 50-70 HRK, you can check the bus schedule here).
You can rent a car right at the airport - there are several rental companies.
If you're taking the ferry from Venice to Porec, after arriving at Marco Polo Airport, take a cab (costs about 30 EUR) to the port. You can also negotiate a transfer with the cruise company, but it's usually more expensive than a cab.