The Welcome Party/Registration on February 17 will also be in the Department of Mathematics and Computer Science, in the "Sala Consiglio" on the first floor.
The Excursion on February 19 will start from Piazza Stesicoro (pinpointed in yellow on the map). Be there at 19:00.
The visit to the monastery ("Monastero dei Benedettini") on February 20 will start at 19:00. We will meet at 18:45 in front of the monastery, which is flagged in green on the map.
The city center is connected to the airport via the Alibus, which leaves every 25 minutes just outside the arrivals area of the Catania Airport. A one way ticket costs 4 Euros and can be bought from the driver. The Alibus stops at the train station and at major locations throughout the city center.
There is a metro station (Giovanni XXIII) just outside the train station. A 90 minute ticket costs 1 Euro and a day pass can be bought for 2 Euros from the automatic machines inside the station. The closest stop to the conference venue is "Milo"; after getting out of the subway, take the shuttle bus stopping in front of the Milo metro station and get off at the stop named "Cittadella Universitaria Est". The bus is free as long as you have a valid metro ticket.
(Note: most of these places don't accept credit cards)