The closest stop to Bastia Poretta airport is Lucciana, which is about 3.3 km from the airport. Casamozza station is about 5.8 km from the airport. A shuttle service is available to get to Bastia train station, more information at +33 4 95 31 06 65.
The closest stop to Campo D'ell'oro airport is Ricanto, which is 2 km from the airport. A shuttle station - Airport runs every hour from 5 am to 10 am and then every half hour from 10 am to 8 pm and finally every hour from 8 pm to 11 pm, more info here.
The closest stops to Calvi Sainte-Catherine airport are Calvi L'Alzeta Suprana (4km) and U Ponte Bambinu (4.5km). The taxi to get to Calvi train station costs around 20 €.
It is quite possible to stop at a station, visit the city and take a next train to get to your destination (except in the suburban of Bastia, Ajaccio and Balagne).