you do hop on/off the bus a designated stops. However, the buses come to those hop on/off locations on a rotational schedule. When you want to hop back on you wait at the stop for a bus to come through. The busses do not wait for you.
they have three different tours if it’s still the same as the last time I did it. Beach, downtown and little Havana areas. You could also pay extra for the boat ride through star island. You do start and end at bayside market if you ride the entire tour with out hopping off.
They have the ins and outs down to a science so it runs smoothly and is a great way to see the city. I highly recommend. We have done it several times and we are sure to bring money to tip the drivers and guides.