The Duomo complex, including the Cathedral, Dome, Baptistery, Bell Tower, and Museum, is situated at Piazza del Duomo in the historic heart of Florence.
Yes, there are several bus stops near the Duomo that allow visitors to reach it comfortably. The Duomo is also withing walking distance of the main train station, Santa Maria Novella (about 15 mins).
Most of the city center of Florence is restricted to cars without a special permit, so the best option would be to find the nearest accessible car park and walk to the Duomo from there.