Train station is only a few minutes by bus or taxi or 15 minutes by foot (a very nice walk through Borgo Albizi, Via del Corso, Via Calzaiuoli, Piazza della Repubblica, Piazza Antinori and Piazza Santa Maria Novella). Bus stop 100 meters. From Pisa airport there are many buses that arrive to Santa Maria Novella train station. If you come by car thee are public and private parkings. Pay attention, you cannot enter with the car in Piazza dei Ciompi and all historical centre in Florence unless you go to a private parking!