San Marino has no airports. The nearest major airport is at Rimini. There are other airports at Ancona, Bologna and Forlì.
San Marino has no railway stations. The nearest major railway station is at Rimini.
You should have no problems driving into San Marino. Border controls do not exist.
San Marino is highly accessible but can take 3-4 hours from the West.
Mostly all free parking, try not to park right at the bottom of the hill, otherwise it's a long way to the top!
There is a 1.5 km cable railway connecting the city of San Marino to Borgo Maggiore.