How much does a taxi ride cost from the airport to the center of Tallinn? What are the alternatives?

So I was wondering how much a taxi ride would cost from Tallinn International Airport to the old town area of Tallinn.

Do buses operate at 23:30-00:00?

Never rode a taxi nor a bus in Estonia, so I'm not sure how they work.. Thanks!

Edit: It would be about a 5km ride and I doubt there's any traffic at that time.