Check with hosts about the local situation. One can obtain a bus pass at a terminal or pay in correct change. Most buses will have both a driver and a conductor. Tickets are purchased from the conductor. Conductors can usually make change for small bills.
Passengers can request the conductor for help in finding the correct stop.
Buses travelling between cities are equally crowded. There are no assigned seats, so get there early. Schedules are more or less adhered to.